ES2999287T3 - Testing system - Google Patents

Abstract

A test system (360) for determining ground features is described. The test system (360) includes a drive means (370) and a test element (100). The test element (100) includes a longitudinal body (110) configured to receive a driving force from the drive means and a penetration end (114); and an array of two or more sensors interspersed along the length of the longitudinal body, each configured to provide information about a ground feature. The sensor array comprises a first sensor (130) spaced a first distance from the penetration end and a second sensor spaced a second, greater distance from the penetration end. In use, the drive means is configured to provide a driving force to the test element to drive the test element into the ground to a first ground depth, wherein the first of the two or more sensors provides information about the ground feature at or through an elevation level as the test element is driven into the ground to the first ground depth; and providing a driving force to the test element to further propel the test element into the soil to a second soil depth, wherein the second of the two or more sensors provides information about the soil characteristic at or through the elevation level as the test element is further propelled into the soil to the second soil depth. (Automatic translation with Google Translate, no legal value)

Description

DESCRIPTION

Test system

The present invention relates to a test system and a test method. In particular, but not exclusively, the present invention relates to a test system for determining soil characteristics and a method for determining said soil characteristics for piling.

Background

To drive a pile into offshore soil, a ram or hammer is typically dropped onto the top of the pile from a certain height. It is known that the characteristics of the soil into which a pile is to be driven can affect the pile's driving capacity and the overall design of the chosen pile. Testing systems are used to predict soil characteristics, from which appropriate pile driving parameters can be selected (e.g., the hammer energy level or the number of ram or hammer blows required to drive the pile to its final position).

These well-known tests include a cone penetration test (CPT), which measures: tip resistance; shaft friction; and/or pore water pressure. For a CPT, all measurements are made at the tip of the test element as it is driven downward into the ground. Therefore, soil characteristics at each elevation are measured only once as the test element is driven into the ground. However, soil characteristics, such as soil friction, can change as a pile is driven into the ground (caused by a mechanism commonly referred to as soil friction fatigue). Therefore, there can be large deviations between the characteristics predicted from such tests and the final characteristics.

In use, monopiles can be subject to large overturning moments as a result of waves acting on the foundation and wind acting on the wind turbine rotor. These moments can be large, for example, up to 1 GN m. Current testing methods lack an effective way to assess the suitability of the soil to support a pile subjected to such moments.

It would be useful to provide an improved testing system/method to better determine the various soil characteristics so that more accurate predictions for piling and in-situ behavior can be made.

WO 02/06793 A 1 discloses a multiple friction sheath penetrometer accessory that provides the unique capability of obtaining a plurality of sheath friction measurements at each measurement depth within a single borehole.

Document CN 106223305 B discloses a dynamic penetrometer that automatically considers energy correction and dynamic response, and the penetrometer includes a falling weight, a stabilized tail and a probe rod in sequence from top to bottom; wherein the upper end of the probe rod is connected with the stabilizer fin, the third extensometer is symmetrically installed on the inner wall of the upper end of the probe rod, and the second acceleration sensor is symmetrically arranged at the lower end of the stabilizer fin.

Document CN 110080194 A discloses a scanning pressure injection instrument comprising a force-bearing device and a power device, the force-bearing device comprising a connection system and a pressure and lifting system, the connection system comprising a pressure sensor and a chuck, and the pressure sensor is fixed to the chuck and arranged between the chuck and the power device.

Summary of the invention

Certain embodiments of the invention provide the advantage that more accurate determinations of soil characteristics can be made, which can inform and subsequently improve piling operations. Embodiments according to the invention are set forth in the independent claims, and further specific embodiments are set forth in the dependent claims. In accordance with a first aspect of the present invention, there is provided a testing system as defined in claim 1.

The provision of an elongated test element with an array of two or more (or a plurality of) sensors interspersed along the body thereof enables a ground feature to be repeatedly measured at a given depth or elevation as the test element is driven into the ground (i.e., measured by each sensor as it passes the given depth). As such, the effect of the driving process on the ground feature can be analyzed to provide a more accurate ground characterization that can be used to perform corresponding piling operations (i.e., on a larger scale). Furthermore, the system provides in-situ measurements, enabling foundation optimization, resulting in a more efficient foundation through optimized design.

Direct comparison of the information provided on a particular elevation or depth level by different sensors (i.e., provided when the test element has reached a different depth) allows for improved terrain characterization, in particular improved dynamic characterization.

Friction sensors allow the measurement of the resistance to insertion experienced by the test element.

Friction can be determined through local measurements on the test element or can be determined through a measurement of the tension on the test element, between two positions on the test element, while the tension difference can be attributed to the friction of the shaft (and potentially the inertial component) of the test element between the two positions.

For example, suitably, at least one of the friction sensors includes or is positioned in a sleeve element surrounding a section of the longitudinal body and/or, suitably, at least one of the friction sensors is configured to determine the difference between the axial stress or strain in the longitudinal body at different longitudinal positions in the longitudinal body. Since the controller is configured to determine the change in resistance to insertion of the test element as the test element is inserted into the ground, the friction fatigue of the surrounding soil can be characterized.

Suitably, the test element comprises at least one additional array of two or more sensors interspersed along the length of the longitudinal body, each of the two or more sensors configured to provide information about an additional terrain characteristic. As such, a single test element is provided that can produce a more complete terrain characterization, including information about multiple terrain characteristics (e.g., at least one of friction, pore water pressure, acceleration) and how this characteristic varies as the test element is introduced into the ground.

Suitably, the two or more sensors in the additional sensor assembly are water pressure sensors. Suitably, the driving means is a pile driving assembly. Suitably, the pile driving assembly is a continuous or discontinuous pile driving assembly.

Suitably, the system further comprises a clamping assembly and/or a stop removably attached to the test element, wherein the insertion force is transferred to the test element through the clamping assembly or stop.

Suitably, the system further comprises an array of at least one acceleration sensor.

Suitably, the pile driving assembly comprises:

a housing defining a chamber, the chamber configured to accommodate a fluid; and activation means coupled to the chamber,

wherein activation of the activation means moves the camera relative to the test element such that the camera moves away from the test element, and

wherein the activation means are configured to release the camera to move it towards the test element so that the camera exerts a force on the test element, to drive the pile into the ground in a controlled manner.

According to a second aspect of the present invention, there is provided a method for determining terrain characteristics as defined in claim 8.

Suitably, the method further comprises determining, using at least one additional set of two or more sensors interspersed along the length of the longitudinal body, information about an additional terrain feature.

Suitably, the method further comprises the step of extracting the evidence item from the ground.

Suitably, the longitudinal body comprises a plurality of segments, wherein the test element is introduced into the ground by at least partially introducing a first segment of the longitudinal body into the ground; attaching a further segment of the longitudinal body to one end of the first segment; and at least partially introducing the further segment of the longitudinal body into the ground.

The means of introduction appropriately comprises:

a housing defining a chamber, the chamber configured to accommodate a fluid; and an actuating means coupled to the chamber,

where the method also includes the steps of:

provide the pile driving assembly with the chamber in a coaxial arrangement with the test element;

activate the activation means so that the camera moves away from the evidence item; and

further activating the activation means to release the camera so that the camera moves towards the test element and exerts a force on the test element, to introduce the test element into the ground in a controlled manner.

In an illustrative example not forming part of the claimed invention, a test element is provided for determining the characteristics of the terrain, the test element comprising:

the evidence element comprising:

a longitudinal body configured to receive an insertion force from an insertion means and a penetration end; and

at least two lateral stiffness sensors spaced apart along the length of the longitudinal body; wherein each of the at least two lateral stiffness sensors is configured to determine the lateral stiffness of the ground at a corresponding elevation level once the test element is inserted to a predetermined depth.

The arrangement of an elongated test element with at least two or a plurality of lateral stiffness sensors allows a lateral stiffness profile of the ground surrounding the test element to be characterized as depth increases. This provides information to enable preparations to determine the suitability of the ground for the expected moments applied to the pile. Suitably, the at least two lateral stiffness sensors comprise a first sensor spaced a first distance from the penetration end and a second sensor spaced a second, larger distance from the penetration end. Suitably, at least one of the lateral stiffness sensors comprises a probe element having: an extended position in which the probe element protrudes from the longitudinal body; and

a retracted position in which the probe element is housed within the longitudinal body.

Suitably, the at least one lateral stiffness sensor comprises an actuating element configured to actuate the probe element from its retracted position to its extended position. Suitably, the actuating element comprises an inflatable sleeve or a hydraulic cylinder. Suitably, the at least one lateral stiffness sensor comprises measuring means configured to measure the force required to move the probe element from its retracted position to its extended position and/or to measure the distance by which the probe element protrudes from the test element in its extended position.

Suitably, at least one of the lateral stiffness sensors further comprises a water pressure sensor for determining the pore water pressure.

In an illustrative example not forming part of the claimed invention, a test system is provided for determining soil characteristics, the test system comprising:

a means of introduction; and

an item of evidence,

wherein the pile driving assembly is configured to deliver a driving force to the driving surface of the test element to drive the test element into the ground. Suitably, the driving means is a pile driving assembly.

Suitably, the pile driving assembly comprises:

a housing defining a chamber, the chamber configured to accommodate a fluid; and activation means coupled to the chamber,

wherein activation of the activation means moves the camera relative to the test element such that the camera moves away from the test element, and

wherein the activation means are configured to release the camera to move it towards the test element so that the camera exerts a force on the test element, to drive the pile into the ground in a controlled manner.

Suitably, the system further comprises a clamping assembly and/or a stop removably attached to the test element, wherein the insertion force is transferred to the test element through the clamping assembly or stop.

In an illustrative example that does not form part of the claimed invention, a method is provided for determining terrain characteristics, wherein the method comprises:

provide an item of evidence comprising:

a longitudinal body configured to receive an insertion force from an insertion means and a penetration end; and

at least two lateral stiffness sensors, wherein each of the at least two lateral stiffness sensors is configured to determine the lateral stiffness of the ground;

insert the test element into the ground to a predetermined depth; and

determine the lateral stiffness of the ground at elevation levels corresponding to each of the lateral stiffness sensors using the at least two lateral stiffness sensors.

Suitably, the step of determining the lateral stiffness of the soil using a lateral stiffness sensor comprises activating the lateral stiffness sensor to move a probe element from a retracted position in which the probe element is housed within the longitudinal body to an extended position in which the probe element protrudes from the longitudinal body. Suitably, the introduction means comprises: a housing defining a chamber, the chamber being configured to accommodate a fluid; and activation means coupled to the chamber,

where the method also includes the steps of:

provide the pile driving assembly with the chamber in a coaxial arrangement with the test element;

activate the activation means so that the camera moves away from the evidence item; and

further activating the activation means to release the camera so that the camera moves towards the test element and exerts a force on the test element, to introduce the test element into the ground in a controlled manner.

In an illustrative example not forming part of the claimed invention, a method is provided for modelling the lateral capacity of ground piles, the method comprising:

provide an item of evidence comprising:

a longitudinal body configured to receive an insertion force from an insertion means and a penetration end; and

at least two lateral stiffness sensors, wherein each of the at least two lateral stiffness sensors is configured to determine the lateral stiffness of the ground;

insert the test element into the ground to a predetermined depth;

Determine the lateral stiffness of the ground at elevation levels corresponding to each of the lateral stiffness sensors using the lateral stiffness sensor; and

use lateral stiffness to predict the lateral capacity of the pile in the ground.

Throughout the description, reference is made to "ground characteristics." As used in this document, this term is intended to indicate a property of the ground, for example, the ground into which a pile can be driven (e.g., soil or sand). Ground characteristics include, but are not limited to, ground friction (i.e., the friction experienced by an object, such as a pile, when moving through or within the ground), ground stiffness (i.e., the resistance of the ground to deformation when subjected to an applied load, e.g., the lateral or radial stiffness of the soil), pore water pressure (i.e., the water pressure within defined pores within the ground), and axial (pile tip) strength. Specifically, the ground characteristics described in this document are those related to, or that have an effect on, piling operations.

As used in this document, the term "depth of ground" shall be understood as a depth below the ground surface. For example, in the context of driving a pile or test element into the ground, the depth of ground of the pile or test element shall be understood as the depth reached by one end of its penetration.

As used herein, the term "lift level" shall be understood to be generally interchangeable with "ground depth." That is, a "lift level" is a depth below a ground surface. However, in the context of driving a pile or test element into the ground, to avoid confusion with the "ground depth" of the pile/test element as a whole, a "lift level" may refer to a depth below a ground surface other than the depth reached by a penetration end thereof. For example, a "lift level" may be a distance from the ground surface reached by a section of the pile/test element once the penetration end thereof has been driven to a specified ground depth (e.g., the ground position corresponding to a sensor positioned on a test element). It shall be understood that "elevation level" may refer to a discrete depth (e.g., 10 m) or a depth level (e.g., 10-12 m), which may correspond, for example, to a stratum or layer of soil/material within the terrain.

As used herein, the term "introduction force" shall be understood to mean a force or pressure applied to insert or push an object in a particular direction. For example, a driving force exerted by an introduction means on a test element is a force used to insert or push the test element into the ground.

Brief description of the drawings

Embodiments of the invention are described below with reference to the accompanying drawings, in which:

Figure 1 illustrates a perspective view of an example of a test element;

Figure 2 illustrates an enlarged view of a segment of the test element of Figure 1;

Figure 3 illustrates a perspective view of a test system including the test element;

Figure 4 illustrates an enlarged view of a region within the test system of Figure 3;

Figure 5 illustrates an internal perspective view of a sensor in a test element;

Figure 6a illustrates a perspective view of a test element with a sensor in a retracted position; and

Figure 6b illustrates the perspective view of the test element of Figure 6a with the sensor in an extended position.

In the drawings, like reference numerals refer to like parts.

Detailed description

This disclosure relates to systems and methods for determining ground characteristics to assist in the placement of monopiles or similar. The systems and methods disclosed herein are suitably, but not exclusively, intended for use in offshore applications, e.g., subsea piling, although some aspects of the disclosure may also be used for onshore applications.

Figure 1 shows a test element 100 for determining ground characteristics. For example, the test element 100 may be used to determine ground characteristics in preparation for piling operations, i.e., the driving of piles or similar structures into the ground.

The test element 100 includes a longitudinal body 110. That is, the test element 100 includes an elongated or thin body that extends longitudinally.

In this example, the longitudinal body 110 comprises a rod or tubular member. In this example, the longitudinal body includes a plurality of segments 120, which may be bolted together in an "end-to-end" arrangement. However, in other examples, the longitudinal body may be a single piece.

In this example, the longitudinal body 110 has a penetration end 114. The penetration end 114 is configured to be the first portion of the test element 100 to enter the ground during insertion. In some examples, the penetration end 114 may be tapered to allow for easier entry into the ground.

Generally, the test element 100 is sized to be smaller than the "final product" structures to be driven into the ground, e.g., a monopile or the like. More specifically, the test element 100 may be sized to be a generally scaled-down version of the monopile. It should be understood that the test element 100 may not be hollow like a monopile. As such, the test element 100 may be driven into the ground to provide test data to help inform the installation of the full-scale "final product" structures.

For example, the test element 100 may have reduced dimensions relative to a full-size monopile by a ratio of about 1:50 to about 1:200, appropriately 1:100. For example, the test element may have a diameter of about 5 cm to about 30 cm, appropriately about 12 cm to 25 cm. In a particular example, for a monopile with a diameter of 10 m and a wall thickness of about 8 cm (e.g., a hollow tube pile), a test element 100 having a diameter of 18 cm (for a solid rod) may be used.

The test element 100 may have a length of between about 15 m and about 50 m, suitably between about 20 m and 35 m in length.

The test element 100 includes at least one set of sensors 130, 140. In this example, the test element includes a first set of sensors 130 and a second set of sensors 140. Referring solely to the set 130 for simplicity (but equally applicable to the set 140), the first set of sensors 130 includes at least two sensors. Any suitable number of sensors 130 may be used in the first set. For example, there may be 5, 10, 15, 20, or more sensors spaced along the length of the test element 100. In the section illustrated in Figure 2, three sensors 130a-c are illustrated. For simplicity, these sensors 130a-c will be referred to when describing the sensor set 130.

The sensors 130a-c are configured to provide information about a terrain feature. That is, each of the sensors 130a-c is configured to provide information about the same terrain feature. In other words, generally, the sensors 130a-c within the array 130 are identical, or identical in function. The second array of sensors 140 is configured to provide information about a different terrain feature. In other words, each sensor 140a-c within the second array of sensors 140 is configured to provide information about the same terrain feature, different from the terrain feature of the sensors 130a-c.

Each of the sensors 130a-c in the array 130 is spaced along the length of the longitudinal body 110. For example, the sensor array 130 includes a first sensor 130a spaced a first distance from the penetrating end 114 and a second sensor 130b spaced a second, larger distance from the penetrating end 114 (and other sensors spaced at increasing distances from the penetrating end 114). In other words, the sensors 130a-c, 140a-c in each array 130, 140 are spaced apart from the other sensors in that array 130, 140 such that the length of the longitudinal body 110 has sensors spaced or distributed along it. This allows a large volume of measurements to be taken and compared, improving the accuracy of the collected data. In this example, the sensor array 130 is distributed along the length of the longitudinal body 110. Alternatively, the sensor array 130 may be distributed only in a portion of the longitudinal body 110, for example in a single segment 120 or in alternating segments.

In general, the sensors 130a-c may be separated by any suitable distance depending on the resolution of the measurements required along the length of the longitudinal body 110. For example, the sensors 130a-c may be separated from each other between about 0.5 m and about 3 m along the length of the longitudinal body 110, suitably between 1 m and 2 m.

Each sensor 130a-c within the array 130 is configured to provide information about the corresponding terrain feature as the test element 100 is driven into the ground. Generally, each sensor 130a-c is configured to provide information about the terrain feature at a number of elevation levels as the test element 100 is driven into the ground. That is, each sensor 130a-c may continuously or intermittently provide information about the surrounding terrain as the test element 100 is driven into the ground.

The information provided by each sensor 130a-c may correspond to a specific elevation level (i.e., a specific depth from the ground surface) or along an elevation level (i.e., along a layer or depth band of the ground, for example, between 10 and 11 m from the ground surface).

The provision of information by a sensor 130a-c may be associated with the activation of the sensor 130a-c at a given time (for example, at intervals as the test element 100 is introduced into the ground).

The first set of sensors 130 are friction sensors 130a-c. The friction sensors may be sensors that measure friction locally or indirectly through measurement and comparison of information at more than one location on the test element. For example, the friction sensors 130a-c may be sleeves that measure friction locally, with the sleeves extending circumferentially around a portion of the outer surface of the longitudinal body. In other examples, the friction sensors 130a-c may measure the increase in axial or compressive load over a length range of the longitudinal body (e.g., over intervals of 1 m or less), allowing wall friction (including inertial components) to be estimated. For example, each friction sensor may be at least one extensometer configured to measure the increase in compressive stress/strain due to shaft friction.

The second set of sensors 140 may include one of the water pressure sensors configured to determine pore water pressure and/or acceleration sensors configured to determine the acceleration of the test element in the ground. In other examples, the test element may include a single set of one of the friction sensors/water pressure sensors/acceleration sensor or the number of sets including any combination of such sensors. In some examples, the penetration end 114 may include a tip sensor configured to measure the resistance of the tip of the penetration end 114.

The test element 100 may include a memory for collecting and storing information generated by the sensors of one or more sensor arrays until the test element 100 is extracted. The sensors are configured to send the information about the ground feature to a controller, for example, via a communication line located within the test element. In this manner, the test element 100 may be monitored during the driving process. Figure 3 illustrates an example of a test system 360 that includes a test element 100 and a driving means 370. Figure 4 illustrates an exploded view of Figure 3. The driving means 370 is configured to provide a driving force to the test element 100 to drive the penetration end 114 of the test element 100 into the ground 380. In this example, the driving means 370 is a pile driving assembly (described below).

In embodiments where the longitudinal body 110 is a single-piece component, the test element 100 may extend within the pile driving assembly (e.g., partially within the hammer of the assembly). As such, the test element 100 is laterally supported by the hammer during driving. In embodiments where the longitudinal body 110 is formed from a plurality of segments 120, the longitudinal body 110 may be assembled beneath the pile driving assembly during driving. For example, a first segment 120 may be partially driven into the ground. Once this segment 120 has penetrated sufficiently into the ground, an additional segment is attached to one end of the first segment for subsequent driving into the ground. As such, force is always exerted on the test element 100 near ground level to prevent buckling of the test element 100.

During a test operation, the insertion means 370 of the test system 360 provides an insertion force to the test element 100. The penetration end 114 of the test element 100 is inserted to a first ground depth as a result of the insertion force. As the test element 100 is inserted into the ground 380 to the first ground depth, the longitudinal body 110 is also partially present in the ground 380. To reach the first ground depth, at least one of the sensors 130 is inserted below the ground surface. During insertion to the first ground depth, the first sensor may provide information about the ground feature at any number of elevation levels (at or through at least one elevation level).

The insertion means 370 then provides an insertion force to the test element 100 to further insert the penetration end 114 of the test element 100 into the ground 380 to a second ground depth (the second ground depth being farther from the surface than the first ground depth). As the test element 100 is further inserted into the ground 380 to the second ground depth, a second/other sensor (located farther from the penetration end 114 relative to the first sensor) may provide information about, or determine, the ground characteristic at or through the same elevation levels as the first sensor.

In other words, as the test element 100 is introduced into the ground, successive sensors within a sensor array (in terms of their longitudinal position along the longitudinal body) can provide information about, or determine, the ground feature at or across an elevation level. In this manner, multiple readings of a ground feature at a particular elevation level can be achieved using a test element 100 (i.e., multiple readings corresponding to multiple sensors), while taking into account the effect that the test element might have on the ground.

It follows that multiple readings can be achieved at multiple elevation levels as the test element is introduced into the ground. That is, one sensor can determine the ground characteristics at multiple elevation levels, with subsequent sensors determining the ground characteristics at those elevation levels. As such, a profile of the ground characteristics with depth can be determined, and changes in this profile associated with the introduction of the test element into the ground can be monitored.

In some embodiments, the insertion forces applied by the insertion means to insert the test element 100 to a first and a second ground depth may be part of a single continuous insertion or blow from the insertion means 370. Alternatively, the insertion forces applied by the insertion means to insert the test element 100 to a first and a second ground depth may result from separate and distinct blows, e.g., a plurality of impacts. Specifically, a first insertion force may be applied to insert the test element 100 to a first ground depth, and a second insertion force may be applied to further insert the test element 100 to a second ground depth.

The controller may be configured to receive and compare information provided by the sensors 130 about the ground feature. That is, the relationship between the ground feature and the depth determined from information provided by a first sensor may be compared to the same relationship determined from information provided by one or more subsequent sensors. As such, the ground may be suitably characterized by taking into account the effects of the test element/pile interaction during insertion.

For example, in aspects of the invention, the controller is configured to determine the change in the driving resistance of the test element 100 as the test element 100 is driven into the ground. The change in driving resistance (or other characteristic) may be used to inform pile driving operations. For example, the change in driving resistance may be used to predict the energy/force levels required to drive a pile to a predetermined depth and/or the number of blows required.

For example, a method for determining a pile response during driving may include: providing or selecting a test element, scaled down from a pile; performing a test operation (as described above) in which a profile of a ground feature is calculated with increasing ground depth and the change in said profile is determined during the driving of said test element; predicting a pile response during a driving operation from information provided by the test operation. The predictions may, for example, result from informing a 1D model of the pile with information provided by the test operation (optionally, the information may be first normalized and parameterized) and calculating or determining the pile response from the model.

Once the test element has been driven to a suitable depth (e.g., between about 20 m and about 50 m, preferably between about 20 m and about 40 m, preferably about 30 m), the test element 100 may be lifted out of the ground 380 such that a monopile may be driven into the ground 380. The test element 100 may be lifted out of the ground 380 using hydraulic cylinders that push or pull the test element 100 upward, for example.

Figures 5 to 6b illustrate another example of a test element 500 for determining terrain characteristics.

In the manner described for test element 100, test element 100 includes a longitudinal body 510 having a penetration end (not shown). Test element 500 may have dimensions corresponding to those described above for test element 100.

In this example, the test element 500 includes at least two lateral stiffness sensors 540 spaced apart along the length of the longitudinal body 510 (only one is shown). Each of the lateral stiffness sensors 540 can measure the lateral stiffness of the surrounding terrain such that the lateral stiffness can be measured at a plurality of points along the length of the test element 500.

Any suitable number of sensors 540 may be used. For example, there may be 5, 10, 15, 20 or more sensors spaced along the length of the test element 500. In general, the sensors 540 may be spaced apart from each other by any suitable distance depending on the resolution of the measurements required along the length of the longitudinal body 510. For example, the sensors may be spaced apart from each other between about 0.5 m and about 3 m along the length of the longitudinal body 110, appropriately between 1 m and 2 m.

In this example, each lateral stiffness sensor 540 is positioned within the longitudinal body 510, and includes a probe element 542. The probe element 542 has a retracted position (shown in Figure 6a) in which the probe element 542 is housed or contained within the longitudinal body 510. In the retracted position, the lateral stiffness sensor 540 does not protrude from the periphery of the longitudinal body 510. This allows for smooth insertion of the probe element 500 into the ground.

Furthermore, the probe element 542 is extendable in a radially outward direction from the longitudinal body 510 to an extended position (shown in FIG. 6b ). Each lateral stiffness sensor 540 includes an actuating element 544 that is configured to actuate the probe element 542 between the extended and retracted position. Any suitable actuating element 544 may be used. For example, the actuating element may be an inflatable sleeve within the test element 500 that biases the probe element 542 outward upon inflation. Alternatively, the actuating element 544 may be a hydraulic cylinder.

Each lateral stiffness sensor 540 includes measuring means configured to measure the force required to move the probe element 542 from its retracted position to its extended position (i.e., measure the force required to move the probe a predetermined amount) and/or measure the distance by which the probe element protrudes from the test element 500 in its extended position (i.e., measure the displacement resulting from a specific applied force). As such, the measuring means can calculate or determine the lateral stiffness from the measured/predetermined force/displacement values.

In use, the test element 500 is introduced by an introduction means to a predetermined depth, for example (for example, between about 20 m and about 50 m, preferably between about 20 m and about 40 m, preferably about 30 m).

Once at the predetermined depth, the lateral stiffness sensors 540 may be activated to determine the lateral stiffness of the ground at elevation levels corresponding to each of the lateral stiffness sensors 540. In some examples, the lateral stiffness sensor 540 may also include an integral water pressure sensor (not shown) to determine the pore water pressure at said elevation levels.

Multiple lateral stiffness measurements along the length of the 500-meter test element allow a profile of the soil's lateral stiffness to be calculated with increasing depth. Such a profile can be used to model or predict the lateral capacity of a pile in the ground (i.e., the distributed lateral load that a pile can apply to the surrounding soil without compromising the pile's orientation or the integrity of the pile within the ground). For example, the lateral stiffness profile can be used to determine the pile's stiffness in the ground. This stiffness is important for determining the frequency of the supporting structure, which must fall within a bandwidth.

For example, a method for determining a pile's response during insertion may include: providing or selecting a test element, scaled down from a pile; performing a test run (as described above) in which a lateral stiffness profile is calculated with increasing depth of ground; and predicting the pile's response from the information provided by the test run.

Predictions can be obtained by feeding a one-dimensional model of the pile with information provided by the test operation (optionally, the information can be normalized and parameterized first) and calculating or determining the pile response from the model.

The method may include an additional processing step for the information provided by the test operation. For example, the maximum capacity/tilt resistance and the lateral stiffness profile may be used to calculate the "earthquake" (i.e., the amount of deformation before plastic deformation occurs).

In general, for the test elements 100 and 500 described above, it is advantageous to use a high-mass/low-acceleration pile-driving system. That is, in this example, a high-mass hammer is used to apply a large force to the test element at low accelerations (compared, for example, to a conventional low-mass/high-acceleration hammer). The lower accelerations reduce stresses on the test element to help ensure that the (potentially fragile) sensors in the test element are not damaged during driving. For example, the lateral stiffness sensors 540 of the test element 500 are not expected to survive the accelerations of conventional impact hammers. In other words, the use of such pile drivers allows a test element with greater sensing capabilities to be used with a lower risk of damage to those sensors during driving.

For example, a pile driver assembly utilizing BLUE Piling Technology™ can be used.

In this example (as illustrated in Figures 3 and 4), the pile driver assembly 370 includes a housing 372 defining a chamber, the chamber being configured to house a fluid, e.g., water. In other words, the chamber provides a generally sealed space configured to house and maintain a volume of fluid therein. The housing 372 may include a valve in a wall thereof, coupled to a fluid source/reservoir (e.g., via a pipe or conduit) to allow the chamber to be filled before or during use. In this manner, the assembly may be transported to the operation site with an empty chamber. The chamber may then be filled to a desired level on-site (either before erecting the chamber or as it is erected and while waiting to be released). It would be understood that the "desired level" may be predetermined to produce a predetermined impact energy to drive a pile into the ground. The water used to fill the chamber may be water pumped from the offshore location, e.g., seawater.

In this example, the pile driver assembly 370 further includes an actuating means 374. In this example, the actuating means 374 includes at least one actuator, for example, a hydraulic or pneumatic actuator.

In this example, the actuators 374 are coupled to both a support structure 376 (e.g., a crane) and the housing 372.

In this example, the triggers are located at an end of the housing 372 that is distal to the test element 100. In particular, the triggers extend downwardly from a portion of the support structure 376 toward the housing 372 and are coupled to an upper end of the housing 372.

In use, the chamber is positioned in a coaxial arrangement with the test element 100. Activation of the activation means 374 displaces the housing/chamber 372 relative to the test element 100 such that the camera moves away from the test element 100. In this example, activation of the activators causes the active length of the activators to decrease by pulling the housing 372 upwardly towards an upper end of the support structure 376. Further activation of the activation means 374 causes the activation means 374 to release the camera such that the camera moves towards the test element 100. As a result, the camera exerts a force on the test element 100, to drive the test element into the ground in a controlled manner.

In general, it is advantageous for the pile-driving assembly used to drive the test element into the ground to be of the same configuration or type as that used to perform subsequent piling operations (i.e., subsequent piling operations utilizing the ground characterization obtained using the test element). This ensures that soil conditions or changes in soil conditions during driving are replicated as closely as possible between the test and piling operations.

For example, the pile driver assembly used for testing operations may be a generally scaled-down version of the pile driver assembly used for piling operations. For example, a "full-scale" pile driver assembly used for piling operations may include a chamber with a volume capable of holding from about 1,000 to 5,000 tons of water (suitable for driving monopiles with a diameter of about 6 to 15 meters into the ground). When the chamber is filled with water, the total mass of the casing (including the water it contains) may be at least 8 times greater than the mass of a typical driven hammer used for piling operations (suitably between 8 and 12 times greater). For example, the mass of a large hydraulic impact hammer may be from about 200 to about 270 tons, while the total mass of a casing with water may be about 2,700 tons.

A "reduced" assembly used for test operations may have dimensions reduced in a ratio of about 1:50 to about 1:200, appropriately 1:100.

It is advantageous if the pile-driving assembly used for piling operations (and therefore also for driving the test element into the ground) produces a low level of vibration during use (e.g., in relation to a vibratory hammer). For example, the use of a vibratory hammer in piling operations would alter the characteristics of the ground during the driving process, reducing the applicability of the measurements obtained with the test element.

Modifications

The insertion force may be transferred to the test element 100, 500 in any suitable manner (in other words, the longitudinal body of the test element may be configured to receive an insertion force from the insertion means in any suitable manner). For example, the test element may include an insertion end, or insertion portion, configured to receive an insertion force from the insertion means (i.e., a blow from a hammer).

Advantageously, the driving force is transferred to the test element 100, 500 in a manner that minimizes the risk of the test element deforming during driving. For example, the test element may include a removable stop, boss, or pin extending laterally from the test element. The pile driving assembly may apply a force to the stop that drives the test element downward. The stop may be initially located a predetermined distance above the ground. Specifically, the predetermined distance may be large enough to allow the test element to be driven downward (without the stop contacting the ground) but also small enough to minimize the unsupported length of the test element between the stop and the ground to reduce the likelihood of buckling. That is, the load is introduced as close to the ground as possible. As the stop approaches the ground, the stop may be extracted and reinserted in a different position for additional impacts.

Alternatively (or additionally), the test system may further include a clamping assembly (e.g., as part of the pile driving assembly) configured to engage the test element at a position close to the ground. The clamping assembly may provide lateral support to the unsupported portion of the test element during driving, or the driving force may be transferred to the test element via the clamping assembly.

The test elements 100, 500 may be made of any suitable material, for example, a high-quality stainless steel.

In some examples, the test element may include soil sampling devices to collect sample portions of the ground for later analysis. The test element may include equipment configured to detect unexploded ordnance. The test element may include detection equipment configured to detect rocks within the ground.

It will be apparent to one skilled in the art that the features described in connection with any of the above-described embodiments may be applied interchangeably among the different embodiments. The above-described embodiments are examples to illustrate various features of the invention. For example, envisioned from this disclosure is a test element that combines aspects of test element 100 (e.g., at least one set of friction sensors or other sensors for determining information during insertion) and test element 500 (e.g., at least two lateral stiffness sensors for determining in-situ lateral stiffness). That is, a plurality of lateral stiffness sensors as described in Figure 5 may be utilized as a second or third set of sensors on test element 100. In this manner, a test element may be provided that can measure both changing soil characteristics during insertion and the in-situ lateral stiffness profile.

Throughout the description and claims of this specification, the terms "comprise" and "contain" and variations thereof mean "including, but not limited to," and are not intended to (and do not exclude) other fractions, additives, components, integers, or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification should be understood to contemplate the plural as well as the singular, unless the context otherwise requires.

Features, integers, characteristics, compounds, chemical moieties, or groups described in conjunction with a particular aspect, embodiment, or example of the invention are to be understood as applicable to any other aspect, embodiment, or example described herein unless they are incompatible therewith. All features disclosed in this specification (including any accompanying claims, abstracts, and drawings), and/or all steps of any method or process so disclosed, may be combined in any combination, except for combinations in which at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any of the foregoing embodiments.

Claims (11)

1. A test system (360) for determining soil characteristics, the test system (360) comprising: a means of introduction (370); and a test element (100) comprising: a longitudinal body (110) configured to receive an insertion force of the insertion means (370) and a penetration end (114); and an array of two or more friction sensors (130a, 130b, 130c) interspersed along the length of the longitudinal body (110), each of the two or more friction sensors (130a, 130b, 130c) being configured to provide information about a terrain feature, wherein the array of two or more friction sensors (130a, 130b, 130c) comprises a first friction sensor spaced a first distance from the penetration end (114) and a second friction sensor spaced a second, greater distance from the penetration end (114); wherein, in use, the introduction means (370) is configured to: providing an insertion force to the test element (100) to insert the penetration end (114) of the test element (100) into the ground to a first ground depth, wherein the first friction sensor of the two or more friction sensors (130a, 130b, 130c) provides information about the ground characteristic at a specific elevation level as the test element (100) is inserted into the ground to the first ground depth; and providing an insertion force to the test element (100) to further insert the penetration end (114) of the test element (100) into the ground to a second ground depth, wherein the second friction sensor of the two or more friction sensors (130a, 130b, 130c) provides information about the ground characteristic at the specific elevation level as the test element (100) is further inserted into the ground to the second ground depth; characterized in that the test system further comprises a controller, the controller being configured to receive and compare information provided by the first and second friction sensors about the ground characteristic at the specific elevation level and to determine the change in resistance to insertion of the test element (100) as the test element (100) is inserted into the ground. 2. A test system (360) as claimed in any preceding claim, wherein the test element (100) comprises at least one additional set of two or more sensors (140a, 140b, 140c) interspersed along the length of the longitudinal body (110), each of the two or more sensors (140a, 140b, 140c) being configured to provide information about an additional terrain feature. 3. A test system (360) as claimed in claim 2, wherein the two or more sensors (140a, 140b, 140c) of the additional set of sensors are water pressure sensors. 4. A testing system (360) as claimed in any preceding claim, wherein the driving means (370) is a pile driving assembly. 5. A test system (360) as claimed in claim 4, wherein the pile driving assembly is a continuous or discontinuous pile driving assembly. 6. A testing system (360) as claimed in any preceding claim, wherein the system further comprises a clamping assembly and/or a stop removably attached to the test element (100), wherein the insertion force is transferred to the test element (100) through the clamping assembly or stop. 7. A test system (360) as claimed in any preceding claim, wherein the pile driver assembly comprises: a housing (372) defining a chamber, the chamber being configured to accommodate a fluid; and activation means (374) coupled to the camera, wherein the activation of the activation means (374) moves the camera with respect to the test element (100), so that the camera moves away from the test element (100), and wherein the activation means (374) are configured to release the camera to move it towards the test element (100) so that the camera exerts a force on the test element, to introduce the test element (100) into the ground in a controlled manner. 8. A method for determining terrain characteristics, the method comprising: providing an introduction medium (370); providing a piece of evidence (100) comprising: a longitudinal body (110) configured to receive an insertion force of the insertion means (370) and a penetration end (114); and an array of two or more friction sensors (130a, 130b, 130c) spaced apart from one another along a length of the longitudinal body (110), each of the two or more friction sensors (130a, 130b, 130c) configured to provide information about a terrain feature, wherein the array of two or more friction sensors (130a, 130b, 130c) comprises a first friction sensor spaced a first distance from the penetration end (114) and a second friction sensor spaced a second, greater distance from the penetration end (114); providing an insertion force to the test element (100) with the insertion means (370), to insert the penetration end (114) of the test element (100) into the ground to a first ground depth; determining, using the first friction sensor of the two or more friction sensors (130a, 130b, 130c), information about the ground characteristic at a specific elevation level as the test element (100) is introduced into the ground to the first ground depth; and providing an insertion force to the test element (100) with the insertion means (370), to further insert the penetration end (114) of the test element (100) into the ground to a second ground depth, determining, using the second one of the two or more friction sensors (130a, 130b, 130c), information about the characteristic of the ground at the specific elevation level as the test element (100) is further inserted into the ground to the second depth of ground, characterized in that the method comprises determining the change in resistance upon introduction to the test element (100) as the test element (100) is inserted into the ground from the information provided by the first and second friction sensors. 9. A method as claimed in claim 8, further comprising determining, using at least one additional set of two or more sensors (140a, 140b, 140c) interspersed along the length of the longitudinal body (110), information about an additional terrain feature. 10. A method as claimed in any one of claims 8 or 9, wherein the method further comprises the step of extracting the test element (100) from the ground. 11. A method as claimed in any one of claims 8 to 10, wherein the introduction means (370) comprises: a housing (372) defining a chamber, the chamber configured to accommodate a fluid; and activation means (374) coupled to the chamber, where the method also includes the steps of: providing the pile driver assembly with the chamber in a coaxial arrangement with the test element (100); activating the activation means (374) such that the camera moves away from the test element (100); and further activating the activation means (374) to release the camera such that the camera moves toward the test element (100) and exerts a force on the test element (100), to introduce the test element (100) into the ground in a controlled manner.