JP2007139454A - Capacity evaluation device of pile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a capacity evaluation device of a pile capable of accurately evaluating the capacity of the pile not subjected to a load test. <P>SOLUTION: The capacity evaluation device of the pile is equipped with an estimate N value calculation means 101 for calculating the estimated N value of a pile driving point from a ground investigation results 107 obtained at a plurality of points, a relational expression forming means 102 for forming the relational expression of the estimated N value with execution data 108 obtained during the execution of the pile 1 corresponding thereto, an evaluated N value calculation means 103 for inputting the execution data of the pile to the relational expression to calculate the evaluated N value of the pile driving point, a support force calculation formula forming means 104 for performing the load test with respect to a plurality of piles of which the evaluated N values are calculated to calculate actually measured support force to form a support force calculation formula from a plurality of the evaluated N values and the actually measured support force, a support force calculation means 105 for inputting the evaluated N value of the pile not subjected to the load test to the support force calculation formula to calculate calculated support force and an output part 106 for displaying the capacity evaluation result of the pile based on the calculated support force. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a performance evaluation apparatus for a pile that investigates the settlement rigidity and supporting force of a pile placed and displays the result.

  Conventionally, the rapid loading test of the pile 1 using an apparatus as shown in FIG. 17 is known (refer patent document 1 etc.).

  This rapid loading test is a test method of the pile 1 devised to eliminate the disadvantages of the static loading test and the dynamic loading test. According to this method, the loading time is about 10 times that of the dynamic loading test. By setting the time to about 200 ms, it is possible to eliminate the influence of the propagation of elastic waves and obtain a highly reliable test result close to a static loading test.

  In the rapid loading test, the cushioning material 2 such as rubber is placed on the pile head 1a via the load meter 4, and the weight 3 is freely dropped thereon to hit the pile 1. Thus, loading time can be lengthened by interposing the buffer material 2 between the weight 3 and the pile head 1a.

  Here, when the weight 3 is dropped, the magnitude of the load acting on the pile head 1a is such that the output value output from the strain gauge (not shown) of the load meter 4 passes through the strain amplifier 5 and the personal computer. Is displayed as a working load.

  Further, the displacement of the pile head 1a can be known by measuring the displacement of the displacement meter target 7a attached to the outer peripheral surface of the pile 1 with the optical displacement meter 7.

The action load and displacement data obtained in this way are arranged to calculate the settlement rigidity and bearing capacity of the pile.
JP 2002-303570 A

  However, the loading test such as the rapid loading test described above is not generally performed on all the piles constructed.

  On the other hand, in recent years, in order to increase the reliability of the pile and to make a rational design, it has been required to check the bearing capacity of as many piles as possible, and the pile can be implemented simply and at low cost. Development of performance evaluation and confirmation means such as support capacity has been desired.

  Furthermore, it is desired to construct the pile 1 with high reliability by measuring the strength of the ground at each depth during the construction of the pile 1 (in other words, the supporting force of the pile at that point).

  Therefore, an object of the present invention is to provide a pile performance evaluation apparatus that can accurately evaluate the performance of a pile that has not been subjected to a loading test.

  In order to achieve the object, the present invention provides a predicted N value calculating means for calculating a predicted N value of a pile driving point from a ground survey result performed at a plurality of points, and a plurality of calculated N values. A load test is performed on the pile to obtain the measured support force, and a support force calculation formula creating means for creating a support force calculation formula from a plurality of the predicted N values and the measured support forces, and loading on the support force calculation formula A pile having a bearing capacity calculation means for calculating the calculated bearing capacity by inputting the predicted N value of the pile that has not been tested, and an output section for displaying a performance evaluation result of the pile based on the calculated bearing capacity. It is a performance evaluation device.

  Further, the present invention provides a predicted N value calculating means for calculating a predicted N value of a pile driving point from ground survey results performed at a plurality of points, and obtained during the construction of the predicted N value and the corresponding pile. A relational expression creating means for creating a relational expression with the constructed construction data, an evaluation N value calculating means for inputting the construction data of the pile into the relational expression and calculating an evaluation N value of the pile driving point, and the evaluation N A bearing force calculation formula creating means for performing a load test on a plurality of piles whose values have been calculated to obtain a measured support force, and creating a support force calculation formula from the plurality of evaluation N values and the measured support force, A bearing capacity calculation means for calculating the calculated bearing capacity by inputting the evaluation N value of the pile that has not been subjected to the loading test in the bearing capacity calculation formula, and an output unit for displaying the performance evaluation result of the pile based on the calculated bearing capacity; It is a performance evaluation device for piles equipped with To.

  Here, in each of the piles, it is preferable that the predicted N value and the calculated supporting force have a plurality of values in the depth direction.

  Moreover, the said invention WHEREIN: The construction data of the pile under construction can be input into the said relational expression, and the said performance evaluation result can also be displayed during construction of a pile.

  The present invention configured as described above calculates the predicted N value of the pile driving point using the ground survey results at a plurality of points, and relates the predicted N value and the result of the loading test to calculate the bearing capacity. And output the performance evaluation result of the pile based on the calculated bearing capacity calculated from it to the output unit.

  For this reason, the performance can be accurately evaluated also about the pile which did not perform the loading test.

  Further, a relational expression is created by associating the predicted N value with the construction data obtained during the construction of the pile, and an evaluation N value is calculated by inputting the construction data of the pile into the relational expression. The bearing capacity calculation formula is created by associating the value and the result of the loading test, and the performance evaluation result of the pile based on the calculated bearing capacity calculated therefrom is output to the output section.

  For this reason, since the predicted N value can be corrected by the construction data and the pile bearing capacity can be calculated more accurately, the performance of the pile which has not been subjected to the loading test can be accurately evaluated.

  Furthermore, in each pile, the performance of a pile can be evaluated three-dimensionally by giving the predicted N value and the calculated supporting force a plurality of values in the depth direction.

  In addition, by creating the relational expression in advance and inputting construction data obtained during construction of the pile to the performance evaluation device in real time, the performance evaluation result of the construction site of the pile currently under construction is displayed. Can be made.

  For this reason, construction management of piles becomes easy, and even if the piles are built to the design depth, if it is confirmed that the supporting force assumed at the time of design is not obtained, the pile length can be extended or the supporting force can be sufficiently increased. When it is confirmed that the piles have been obtained, the piles can be reasonably constructed such as by shortening the piles.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram showing a configuration of a performance evaluation apparatus 100 for a pile 1 according to the present embodiment.

  First, when it demonstrates from a structure, the performance evaluation apparatus 100 of the pile 1 by this Embodiment will calculate the predicted N value calculation means 101 which calculates the predicted N value of a pile placement point from the ground investigation result 107 performed in the some point. And a relational expression creating means 102 for creating a relational expression between the predicted N value and the construction data 108 obtained during construction of the corresponding pile 1, and inputting the construction data 108 of the pile 1 into the relational expression The evaluation N value calculation means 103 for calculating the evaluation N value of the pile driving point, and the load test is performed on the plurality of piles 1 for which the evaluation N value is calculated, and the actually measured support force (load test result 109) is obtained. A support force calculation formula creating means 104 for creating a support force calculation formula from a plurality of the evaluation N values and the measured support force, and an evaluation N value of the pile 1 that has not been subjected to a loading test is input to the support force calculation formula. Calculate supportive power That the supporting force calculating means 105, and an output unit 106 for displaying the results of performance evaluation pile 1 based on the calculated support force.

  At the construction site where the pile 1 is placed, a ground survey is conducted in order to know the ground condition of the place. The ground survey result 107 used here is an N value obtained by performing tests such as a standard penetration test (hereinafter referred to as SPT) and a Swedish sounding test (hereinafter referred to as SWS) on the in-situ ground. Etc. A plurality of N values obtained by this ground survey are measured for each unit depth.

  However, these ground survey results 107 are not necessarily performed at the pile driving point where the pile 1 is to be driven, and moreover, only a smaller number of surveys are generally performed compared to the number of piles 1 to be driven. Absent.

  Therefore, it is assumed that the ground state at the pile placement point is predicted by the predicted N value calculation means 101 by effectively using the ground survey result 107 performed before the construction of the pile 1.

  As shown in FIG. 2, the predicted N value calculating means 101 predicts the ground condition at the pile driving point with high accuracy by using the ground investigation results 107 at a plurality of boring points B1 to B4.

  As shown in FIG. 2, when the distance between the boring points B1 to B4 and the pile 1 is represented by r1 to r4, for example, the predicted N value of the placing point of the pile 1 can be estimated by the following weighted cumulative average equation. .

N _Y = (ΣNi / ri) / (Σ1 / ri) = (N1 / r1 + N2 / r2 + N3 / r3 + N4 / r4) / (1 / r1 + 1 / r2 + 1 / r3 + 1 / r4) (Equation 1)
Here, N1-N4 denotes a N values measured by each boring point B1 to B4, _{N Y} denotes the predicted N value. Further, since the N value is measured for each unit depth at each of the boring points B1 to B4, a plurality of N value data is included in N1 to N4, and the predicted N value _NY is also included in the depth. Calculate as the corresponding value.

  On the other hand, during construction of the pile 1, data such as torque, pressure input, rotation speed, penetration speed, and number of hits are obtained as construction data.

  Among these construction data, the data on torque, pressure input and rotation speed are considered to be most dependent on the properties of the ground, and it was confirmed that the relationship between torque and N value is particularly correlated.

Therefore, in the relational expression creating means 102, assuming that the predicted N value _NY is the N value of the pile driving point, construction data and regression analysis are performed to create a relational expression.

  For example, regression analysis is performed by the following relational expression using the torque T as a parameter to obtain constants a and b which are unknowns.

N _Y = a · T ^b (Formula 2)
The evaluation N value calculation means 103 calculates the evaluation N value _NH calculated by inputting the torque T, which is the construction data, into (Equation 2). This evaluation N value _NH can be said to be a value obtained by correcting the predicted N value _NY of the pile driving point estimated based on the ground survey result 107 based on the construction data.

Next, a description will be given of a configuration in which the bearing capacity calculation formula is created by the bearing capacity calculation formula creation means 104 and the bearing capacity of the pile is calculated from the evaluation N value _NH .

  The supporting force Pu of the pile can be calculated by, for example, the following supporting force calculation formula.

Pu = (α · A _p ) · N _p + (β · φ) ΣN _h · L _h (Equation 3)
Here, alpha is bearing capacity coefficient of pile tip, beta is skin friction coefficient of the pile circumference, A _p is the effective cross-sectional area of the pile tip, phi is the circumference of the pile, L _h is the pile of h interval length , N _p is N values of pile tip, N _h denotes the N values of the pile circumference of h intervals.

  Here, since the pile support force Pu and the two constants α and β are unknown, the measured support force of the pile obtained as a result of a load test such as a rapid load test described later is substituted into (Equation 3). The remaining unknowns α and β are obtained.

That is, a load test is performed on at least two piles 1 among the plurality of piles 1 for which the evaluation N value _NH is calculated, and the measured support force as the load test result 109 is Pu, and the pile tip and the pile circumference The evaluation N values N _H corresponding to the N values (N _p , N _i ) are respectively input to (Equation 3) to obtain two unknowns α and β.

The bearing capacity calculation means 105 calculates the calculated bearing capacity of the pile 1 from the evaluation N value _NH using the bearing capacity calculation formula (Formula 3) created in this way.

The calculated supporting force of the pile 1 calculated in this way can be output as a performance evaluation for each pile 1, but when constructing each pile 1 as shown in FIG. 3, for example, 20 to 50 cm Each time the pile 1 is driven in, the support force Pu (z) of the pile 1 at that depth (Z direction) is calculated based on the evaluation N value _NH , and the result of determining the support force is rank 0-10 Can be classified and output.

  Furthermore, the rank at each depth is displayed as a numerical value, and coloring according to the rank is performed so that the depth with high supporting power can be determined at a glance.

  Such a performance evaluation result of the pile can be obtained for the pile 1 subjected to the loading test and the pile 1 from which other construction data can be obtained, and as shown in FIG. The support force of the pile 1 can be grasped.

  That is, in the past, the supporting force related to the one or two piles 1 subjected to the loading test was only obtained discretely, but the pile 1 that was not subjected to the loading test as in the present invention is also easy during construction. If the supporting force can be calculated based on the construction data obtained in the above, it becomes possible to evaluate the visualized three-dimensional ground and the supporting force of the pile 1.

  Next, a rapid loading test will be described as one of the loading tests for calculating the bearing capacity of the pile 1.

  FIG. 4 is a diagram showing a schematic configuration of the rapid loading test.

  First, when it demonstrates from a structure, the measuring device 10 as a load meter is mounted in the pile head 1a of the pile 1 used as the investigation object of subsidence rigidity and supporting force, and the shock absorbing material 2 is mounted on it.

  For the buffer material 2, a rubber material, a polymer material such as urethane elastomer, a steel coil spring, a disc spring, a shock absorber, or the like is used.

  When the weight 3 is freely dropped from above the cushioning material 2, the cushioning material 2 is hit and the load is transmitted to the pile head 1 a through the measuring device 10. In addition, the weight 3 may be lowered with a hydraulic hammer or the like to hit the cushioning material 2.

  The measuring instrument 10 measures the load transmitted to the pile head 1a. As shown in FIGS. 5 and 6, the measuring instrument 10 is mainly composed of an inner cylinder 10b as a cylindrical tube and an outer cylinder 10c arranged on the outer side thereof.

  The inner cylinder 10b is a member that transmits force between the cushioning material 2 and the pile head 1a, and is formed of a high-strength material such as a steel material.

  A strain gauge 10a is attached to the outer peripheral surface of the inner cylinder 10b. When the inner cylinder 10b is distorted by an applied load, the strain gauge 10a outputs the strain as an output value, so that the load acting can be known. .

  The outer cylinder 10c is disposed outside the inner cylinder 10b so as to protect the strain gauge 10a, and the impact force of the weight 3 does not act on the outer cylinder 10c.

  A hydraulic load cell or the like can be used as a load meter.

  Further, the accelerometer 11 is attached to the outer peripheral surface of the inner cylinder 10b in the same manner as the strain gauge 10a.

  As the accelerometer 11, for example, a piezoelectric accelerometer having a sensitivity of 10 mV / g, a measurement range of 0.003 to 500 g, and a frequency range of 0.7 to 11 Hz can be used.

  As shown in FIG. 5, two cables 14, a load output cable 14 a and an acceleration output cable 14 b, are connected to the measuring instrument 10. By attaching the accelerometer 11 to the same location as the strain gauge 10a that detects the applied load in this way, it is possible to prevent wiring from being complicated at the test site.

  The output value transmitted by the cable 14 is amplified by the dynamic strain amplifier 12 and sent to the personal computer 13 as a processing unit (see FIG. 4).

  An output value output from the strain gauge 10a and the accelerometer 11 and amplified by the dynamic strain amplifier 12 is digitally converted by the AD converter and input to the personal computer 13.

  Then, the applied load is calculated from the input output value of the strain gauge 10a, and the displacement is calculated from the output value of the accelerometer 11.

  In order to calculate the displacement from the output value of the accelerometer 11, for example, the output value is integrated twice in time series by the linear acceleration method (see Junsuke Osaki, “Introduction to new ground motion spectrum analysis”, Kashima Publishing Association). That's fine.

  FIG. 7A shows the relationship between time and displacement calculated by this linear acceleration method. Comparing the displacement calculated by the “linear acceleration method” with the “actual value” measured by the conventional optical displacement meter 7, it can be seen that after the maximum displacement has occurred, the two deviate from each other.

  On the other hand, since the displacement of the output value can be shown by the method of Osaki (see Jungo Osaki, “Introduction to new ground motion spectrum analysis”, Kashima Publishing Co., Ltd.), FIG. ".

  The displacement by the “Osaki correction method” is very similar to the displacement shape of the “actually measured value”, but there is a deviation as a whole.

  Therefore, a displacement calculation method in the pile measuring apparatus according to the present embodiment in which an “actual value” by the optical displacement meter 7 cannot be obtained will be described below with reference to FIG.

First, a point where the displacement of the “linear acceleration method” calculated from the output value of the accelerometer 11 is “0” is set as a starting point (t ₁ ) immediately before loading by the weight 3. Then, the displacement of the starting point (t ₁ ) of the “Osaki correction method” is made to coincide with the 0 point as shown in “0 point correction” of FIG. t ₂ ).

On the other hand, the residual displacement of the pile head 1a after loading is measured by leveling or the like. When the final measurement point (t ₃ ) of “0 point correction” is made to coincide with this residual displacement, a corrected displacement as shown in “0 + residual correction value” in FIG. 7B is obtained.

  In this way, by correcting the displacement calculated from the output value output from the accelerometer 11, the output value obtained from the accelerometer 11 can be brought close to the actual displacement of the pile head 1a.

  That is, when comparing the “actual value” and “0 + residual correction value”, there is a good agreement in the data near the unloading point where the displacement of the pile head 1a is reversed. The “correction value” is used as the displacement of the pile 1.

  Next, an example of a matching method for calculating the supporting force from the relationship between the displacement (settlement amount) of the pile 1 thus calculated and the load acting on the pile head 1a will be described.

  Here, a matching model using a spring (k value) and a dashpot (damping constant C) arranged in parallel and a damping model as shown in FIG. 8A will be described.

  In this method, first, the calculated displacement obtained by gradually changing the k value of the spring is compared with the “0 + residual correction value” (displacement of the pile 1) calculated above, resulting in the smallest error. Calculate the optimal k value.

  The calculation of the static resistance component P (t) corresponds to δ (t) from the displacement δ (t) and the optimum k value at the intersection of the hysteresis curve and the optimum k value shown in FIG. P (t) is calculated by (Equation 4).

P (t) = k · δ (t) (Equation 4)
Then, an attenuation constant C obtained from the matching point and the maximum velocity Vmax is obtained from (Equation 5), and P ′ (t) corrected for velocity by (Equation 6) is calculated from this C and velocity V (t).

C = ΔP / Vmax (Formula 5)
Here, ΔP = Pmax−P (t)
P ′ (t) = P (t) −C × V (t) (Formula 6)
As shown in FIG. 8B, the load-displacement relationship is estimated by performing load correction between (Equation 5) and (Equation 6) between the starting point A and the position B of the maximum speed Vmax. Linear interpolation is performed between the position B of the velocity Vmax and the matching point C.

  FIG. 9 shows a result of arranging the output values of the measuring instrument 10 and the accelerometer 11 obtained when the rapid loading test is performed on a certain pile 1 by applying the matching method described above.

  The result of FIG. 9 is a summary of the results of hitting the pile head 1a by the weight 3 while changing the drop height four times. From the matching points calculated at each drop height, the pile head load and The estimated curve of the pile head displacement (solid line in FIG. 9) was calculated.

  Various methods for calculating the bearing capacity of the pile 1 have been proposed. For example, the ultimate load (about 115 kN) obtained from the estimated curve (solid line) in FIG. 9 can be used as the bearing capacity of the pile 1. .

  Next, the processing flow of the performance evaluation device 100 for the pile 1 according to the present embodiment will be described with reference to the flowchart of FIG.

  First, SWS (Swedish sounding test) is performed at a plurality of (preferably four or more) points on the ground of the construction site site where the pile 1 is to be placed (step S1).

Then, the N value Ni measured by the SWS and the distance ri between the boring point Bi and the pile 1 are input to (Equation 1) to calculate the predicted N value _NY (step S2).

Subsequently, the pile 1 is constructed at the pile driving point where the predicted N value _NY is calculated, construction data such as torque T is collected, and a relational expression between the predicted N value _NY and the construction data (Formula 2) Is created (step S3).

And construction data (torque T) is input into this relational expression (Formula 2), and evaluation N value _NH is calculated (step S4).

  Moreover, a rapid loading test is performed with respect to two or more of the constructed piles 1 (step S5), and the actual supporting force is calculated from the test result (step S6).

Supporting force calculation formula from this way the actual support force which is determined by the evaluation N value N _H create a (Formula 3) (step S7), and the evaluation value N N _H on the supporting force calculation formula (Equation 3) The calculated support force is calculated by inputting (step S8).

  This calculated support force is output as a numerical value as it is as a performance evaluation result of the pile 1 or a determination rank determined based on the calculated support force (step S9).

The performance evaluation device 100 for the pile 1 according to the present embodiment configured as described above calculates the predicted N value _NY of the pile placing point using the ground survey results 107 at a plurality of points, and the predicted N value. A relational expression is created by associating _NY with construction data obtained during construction of the pile 1.

And the evaluation N value _NH is calculated by inputting the construction data of the pile 1 into the relational expression, the evaluation N value _NH is related to the result of the loading test, and the bearing capacity calculation formula is created. The pile performance evaluation result based on the calculated calculated support force is output to the output unit 106.

  For this reason, also about the pile 1 which did not perform the loading test, the performance can be evaluated accurately.

  Moreover, in each pile 1, ..., the performance of a pile can be evaluated three-dimensionally by giving a plurality of values to the said prediction N value, the said evaluation N value, and the said calculation support force in the depth direction.

  In addition, by creating the relational expression in advance and inputting construction data obtained during the construction of the pile 1 to the performance evaluation device 100 in real time, the performance evaluation result of the placing point of the pile 1 being constructed instantaneously Can be displayed.

  That is, since the measurement result derived from the construction data can be visualized in three dimensions in real time, it is possible to easily grasp the relationship with other piles placed in the vicinity and changes in variations.

  In addition, when a load test is performed on many piles 1,... At the same site, the bearing capacity characteristics of the pile 1 are relatively determined by the construction data even if the relationship between the displacement and the applied load is not strictly measured. Since it can be confirmed, it is useful when used for performance evaluation as construction management.

  For this reason, the construction management of the pile 1 becomes easy, and even if the pile is built to the design depth, if it is confirmed that the supporting force assumed at the time of design is not obtained, the pile length can be extended or the supporting force can be sufficiently increased. If it can be confirmed that the pile has been obtained, the pile can be reasonably constructed, such as by shortening the pile.

  Hereinafter, an Example demonstrates the examination result which confirmed that the performance of the pile 1 can be evaluated accurately according to the structure of the performance evaluation apparatus 100 of the pile 1 of the said embodiment.

  In carrying out this examination, as shown in FIG. 11, 30 piles were placed in a lattice shape at intervals of 3 m. In addition, SPT and SWS ground surveys were conducted at five locations on the site.

  FIG. 12 is a diagram showing the relationship between the number of drilling points used for prediction and the standard deviation when one of these ground survey results 107 is predicted from the other ground survey results 107.

  As can be seen from FIG. 12, the standard deviation decreases as the ground survey results 107 used for prediction in both SPT and SWS increase, and the variation in prediction decreases.

  In addition, although the following description is performed based on the ground investigation result 107 by SWS, the same result can be confirmed also when the ground investigation result 107 by SPT is used.

  FIG. 13 shows a predicted N value obtained by substituting the ground survey result 107 at four boring points into (Equation 1) and predicting an N value at the remaining one boring point, and an N value actually measured by SWS. It is the figure which showed the relationship.

  Thus, if the predicted N value of a pile driving point is calculated | required using the ground investigation result 107 of four or more places, the N value of a pile driving point can be calculated favorably.

  And the figure which showed the relationship between the predicted N value of the pile placing point calculated in this way and the torque in the construction data obtained during the construction of the pile 1 is shown in FIG.

  As shown in FIG. 14, it can be said that there is a correlation between the predicted N value calculated from the SWS result and the torque.

  Further, FIG. 15 shows the bearing force obtained by putting the actually measured bearing force Pu and the predicted N value obtained as a result of the test on the pile 1 subjected to the rapid loading test into the bearing force calculation formula (Equation 3). The relationship with Pu was shown.

  Here, there are two types of piles placed in this embodiment: a tip closed pile (type 1) in which the tip of the pile is closed, and a tip open pile (type 2) in which the tip is opened. 15 and the following FIG. 16 show the results of Type 1.

  In FIG. 16, the measured support force Pu obtained as a result of the rapid loading test and the evaluation N value calculated by substituting the torque into the relational expression (formula 2) are obtained by entering the support force calculation formula (formula 3). The relationship with the supporting force Pu was shown.

  When FIG. 15 and FIG. 16 are compared with each other, there is a good correlation between the actual measurement value and the predicted value, but the supporting force calculated based on the evaluation N value (FIG. 16) is the predicted N value. It can be said that the standard deviation σ and the coefficient of variation cv are smaller than the supporting force calculated based on FIG. Μ represents an average value.

  The same result was confirmed for Type 2.

  Although the best embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes that do not depart from the gist of the present invention are possible. Are included in the present invention.

  For example, in the present embodiment, the calculation support force is calculated by calculating the evaluation N value from the prediction N value and the construction data. However, the present invention is not limited to this, and the prediction N value is obtained without obtaining the evaluation N value. You may evaluate the performance of the pile directly by calculating the supporting capacity. In that case, the constants α and β are obtained by substituting the predicted N value into the bearing capacity calculation formula (Formula 3).

  In the above embodiment, a rapid loading test in which a weight is dropped as a loading test was performed. Any loading test result such as a loading test in which an external force is applied to the pile head 1a by the reaction mass launched by burning may be used.

  Further, the weighted cumulative average equation (Equation 1), the relational equation (Equation 2), the bearing capacity calculation equation (Equation 3), etc., for estimating the predicted N value shown in the above embodiment are not limited to these. For example, an equation for squaring the distance ri can be applied to the weighted cumulative average equation.

  Furthermore, in the said embodiment, as shown in FIG. 3, the performance evaluation result of the pile was displayed in the three-dimensional position, but it is not limited to this, for example, the position of the depth (Z direction) is as coordinate data. The positions in the X and Y directions may be displayed in a two-dimensional manner as a whole so as to be displayed side by side without following the coordinate data.

It is explanatory drawing explaining the schematic structure of the performance evaluation apparatus of the pile of the best embodiment of this invention. It is explanatory drawing for demonstrating the method of estimating the ground condition of the placement point of a pile from a some boring investigation result. It is the figure which showed the example of a display of the display part which displayed the performance evaluation result of the pile in the three-dimensional position. It is explanatory drawing explaining schematic structure of the rapid loading test of a pile. It is explanatory drawing explaining the connection state of a measuring device and dynamic strain amplifier. It is an arrow view of the AA line direction of FIG. (A) is the relationship figure of the displacement and elapsed time which compared the output value and measured value of the accelerometer, (b) is explanatory drawing explaining the correction method of the output value of an accelerometer. (A) is explanatory drawing explaining the method of calculating a static component in the bearing capacity calculation of a pile, (b) is explanatory drawing explaining the estimation of the load-displacement relationship by a matching method. It is a related figure of pile head load-pile head displacement for calculating bearing capacity. It is a flowchart explaining the flow of a process of the performance evaluation apparatus of a pile. It is the top view which showed the placement position and ground investigation position of the pile which were placed in order to confirm the effect of the performance evaluation apparatus of a pile. It is the figure which showed the relationship between the number of the boring points used for calculating the predicted N value, and the standard deviation. It is the figure which showed the relationship between N value measured by the ground investigation, and the predicted N value of the point. It is the figure which showed the relationship between the torque as construction data, and predicted N value. It is the figure which showed the relationship between the bearing capacity of the pile calculated | required from the rapid loading test, and the bearing capacity of the pile calculated from the predicted N value. It is the figure which showed the relationship between the bearing capacity of the pile calculated | required from the rapid loading test, and the bearing capacity of the pile calculated from evaluation N value. It is explanatory drawing explaining schematic structure of the measuring apparatus of the pile of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Performance evaluation apparatus 101 Predicted N value calculation means 102 Relational expression preparation means 103 Evaluation N value calculation means 104 Support force calculation formula preparation means 105 Support force calculation means 106 Output part 107 Ground investigation result 108 Construction data 109 Loading test result (measurement support) Power)

Claims (4)

A predicted N value calculating means for calculating a predicted N value of a pile driving point from ground survey results conducted at a plurality of points;
A bearing force calculation formula creating means for performing a load test on a plurality of piles for which the predicted N value has been calculated to obtain an actually measured support force and creating a support force calculating formula from the plurality of the predicted N values and the actually measured support force When,
A bearing capacity calculation means for calculating the calculated bearing capacity by inputting the predicted N value of the pile that has not been subjected to a loading test in the bearing capacity calculation formula;
A pile performance evaluation apparatus comprising: an output unit that displays a performance evaluation result of the pile based on the calculated support force. A predicted N value calculating means for calculating a predicted N value of a pile driving point from ground survey results conducted at a plurality of points;
A relational expression creating means for creating a relational expression between the predicted N value and the construction data obtained during construction of the pile corresponding thereto;
An evaluation N value calculating means for inputting the construction data of the pile to the relational expression and calculating an evaluation N value of the pile driving point;
A bearing force calculation formula creating means for performing a load test on a plurality of piles for which the evaluation N value has been calculated to obtain an actually measured support force and creating a support force calculation formula from the plurality of the evaluation N values and the actually measured support force When,
A bearing capacity calculation means for calculating the calculated bearing capacity by inputting the evaluation N value of a pile that has not been subjected to a loading test in the bearing capacity calculation formula;
A pile performance evaluation apparatus comprising: an output unit that displays a performance evaluation result of the pile based on the calculated support force.   3. The pile performance evaluation apparatus according to claim 1, wherein in each of the piles, the predicted N value and the calculated supporting force have a plurality of values in a depth direction. In each of the piles, the predicted N value and the calculated supporting force have a plurality of values in the depth direction, and the construction data of the pile under construction is input to the relational expression, and the performance evaluation result is being applied to the pile. The pile performance evaluation apparatus according to claim 2, wherein the pile performance evaluation apparatus is displayed.

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