A method for determining the effective depth and extent of dynamic compaction reinforcement
By setting up multiple monitoring points in the dynamic compaction test, analyzing the changes in vibration acceleration and pore water pressure, and calculating the reinforcement effect, the problem of difficulty in determining the reinforcement depth and range in dynamic compaction foundation treatment was solved, and precise control over the impact on construction was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CCCC FOURTH HARBOR ENG CO LTD
- Filing Date
- 2023-07-28
- Publication Date
- 2026-05-26
AI Technical Summary
Existing technologies make it difficult to accurately determine the effective reinforcement depth and range in dynamic compaction foundation treatment, resulting in uncontrollable impacts of construction vibrations on the stability and safety of wharf structures.
By conducting multiple sets of dynamic compaction tests on the construction foundation, setting up multiple monitoring points, and using acceleration sensors and pore water pressure sensors, the changes in vibration acceleration and pore water pressure were analyzed, the improvement rate of reinforcement effect was calculated, and the effective reinforcement depth and range of dynamic compaction were determined.
Precisely determine the reinforcement depth and scope of dynamic compaction foundation treatment to reduce the impact of construction on surrounding buildings and the environment, and improve construction quality and safety.
Smart Images
Figure CN117188425B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of foundation reinforcement technology, and in particular relates to a method for determining the effective reinforcement depth and range of dynamic compaction. Background Technology
[0002] Dynamic compaction is an effective reinforcement measure in foundation treatment engineering, and it is often used in large-scale projects such as wharves, ports, and airports. During the construction of projects such as wharves, the area immediately behind the wharf structure is often backfilled land, such as caisson wharves, block wall wharves, and sheet pile wharves. All backfilled foundations require foundation treatment to meet the corresponding bearing capacity and settlement requirements.
[0003] However, the intense ground vibrations during dynamic compaction foundation treatment often lead to deformation of the wharf structure, affecting its stability and safety. Therefore, a boundary line is typically established between the wharf structure and the foundation treatment area. Based on engineering experience, this boundary line is generally set at 80m to 100m. In practice, when reinforcing different soil types with different energies, the permissible distance for high-energy dynamic compaction equipment varies depending on the type of wharf structure. Within the boundary line area, i.e., in the vicinity of the wharf structure, low-energy compaction methods, such as vibratory rolling, rapid compaction, and low-energy dynamic compaction, must be employed with appropriate process control measures to meet the safety and stability requirements of the wharf structure.
[0004] Currently, research on vibration in dynamic compaction methods, both domestically and internationally, largely remains at the laboratory and numerical simulation stages, with limited research related to practical engineering applications. Further analysis and summarization are needed to determine the vibration effects of compaction and other densification methods based on actual engineering projects, thereby deriving the vibration energy transfer laws during the dynamic compaction foundation treatment process. Therefore, when using dynamic compaction for foundation treatment, determining the effective reinforcement depth and range in advance is crucial for controlling construction quality and ensuring safety during construction. Summary of the Invention
[0005] The purpose of this invention is to provide a method for determining the effective reinforcement depth and range of dynamic compaction, which can accurately obtain the effective reinforcement depth and range of dynamic compaction.
[0006] This invention is achieved through the following technical solution:
[0007] A method for determining the effective depth and extent of dynamic compaction reinforcement includes the following steps:
[0008] Multiple sets of dynamic compaction tests were carried out on the construction foundation. In the multiple sets of dynamic compaction tests, the total compaction energy was a constant value. The number of compaction blows or the compaction energy of each compaction blow were varied so that the number of compaction blows and the compaction energy corresponding to each compaction blow constituted a set of dynamic compaction tests.
[0009] Before each set of dynamic compaction tests, multiple sets of monitoring points are set at intervals in the construction foundation around the compaction point selected for the dynamic compaction test. Each set of monitoring points includes multiple rows of monitoring points with different horizontal distances from the compaction point. Each row of monitoring points includes several monitoring points arranged at intervals along the vertical direction. A sensor unit is set on each monitoring point. The sensor unit includes an acceleration sensor and a pore water pressure sensor.
[0010] Before each set of dynamic compaction tests, the initial soil data of each monitoring point is obtained, and after each set of dynamic compaction tests, the soil data after compaction of each monitoring point is obtained, as well as the acceleration data and pore water pressure data collected by the sensor unit. Based on the initial soil data and the soil data after compaction of each monitoring point, the reinforcement effect improvement rate of each monitoring point is calculated. The soil data includes at least one of the standard penetration test blow count or penetration resistance.
[0011] For each group of dynamic compaction tests, based on the improvement rate of the reinforcement effect at each monitoring point, the acceleration data and pore water pressure data collected by the sensor unit at the monitoring point, the reinforcement analysis data for each monitoring point is calculated. The reinforcement analysis data includes the improvement rate of the vertical reinforcement effect, the improvement rate of the vertical acceleration, the improvement rate of the vertical pore water pressure, the first ratio of the improvement rate of the vertical reinforcement effect to the improvement rate of the vertical acceleration, and the second ratio of the improvement rate of the vertical reinforcement effect to the improvement rate of the vertical pore water pressure along the depth direction of the monitoring point; and the improvement rate of the horizontal reinforcement effect, the improvement rate of the horizontal acceleration, the improvement rate of the horizontal pore water pressure, the third ratio of the improvement rate of the horizontal reinforcement effect to the improvement rate of the horizontal acceleration, and the fourth ratio of the improvement rate of the horizontal reinforcement effect to the improvement rate of the horizontal pore water pressure along the direction away from the compaction point.
[0012] Based on the reinforcement analysis data of monitoring points obtained from multiple sets of dynamic compaction tests, the effective reinforcement depth and horizontal range of dynamic compaction on the construction foundation were determined.
[0013] Furthermore, based on the reinforcement analysis data from monitoring points obtained from multiple sets of dynamic compaction tests, the steps for determining the effective reinforcement depth and horizontal range of dynamic compaction on the construction foundation include:
[0014] Monitoring points with the same relative position to the compaction point in multiple sets of dynamic compaction tests are taken as the same monitoring point. Multiple reinforcement analysis data of the monitoring point are compared to obtain the maximum vertical acceleration increase rate, maximum vertical pore water pressure increase rate, maximum horizontal acceleration increase rate, maximum horizontal pore water pressure increase rate, maximum first ratio, maximum second ratio, maximum third ratio and maximum fourth ratio corresponding to the monitoring point.
[0015] In each column of monitoring points, monitoring points are selected in order from top to bottom. The first monitoring point that meets the first selection condition is taken as the first target monitoring point. Then, the burial depth of the first target monitoring point in the construction foundation is obtained, resulting in multiple burial depths. The first selection condition is that the maximum first ratio and the maximum second ratio of the monitoring point are both less than the preset first threshold, and the maximum vertical acceleration increase rate and the maximum vertical pore water pressure increase rate of the monitoring point are both less than the preset second threshold.
[0016] The multiple burial depths obtained were compared, and the largest burial depth was taken as the effective reinforcement depth of dynamic compaction on the construction foundation.
[0017] For each group of monitoring points, several monitoring points with the same burial depth are grouped into the same row of monitoring points to obtain several rows of monitoring points. Monitoring points are selected in each row of monitoring points in the order of being furthest from the compaction point. The first monitoring point that meets the second selection condition is taken as the second target monitoring point. Then, the horizontal distance between the second target monitoring point and the compaction point is obtained to obtain multiple horizontal distances. The second selection condition is that the maximum third ratio and the maximum fourth ratio of the monitoring point are both less than the preset first threshold, and the maximum horizontal acceleration increase rate and the maximum horizontal pore water pressure increase rate of the monitoring point are both less than the preset second threshold.
[0018] The obtained horizontal distances are compared, and the largest horizontal distance is taken as the effective horizontal reinforcement range of dynamic compaction on the construction foundation.
[0019] Furthermore, in the step of conducting multiple sets of dynamic compaction tests on the construction foundation, four sets of dynamic compaction tests were conducted on the construction foundation, namely the first set of dynamic compaction tests, the second set of dynamic compaction tests, the third set of dynamic compaction tests, and the fourth set of dynamic compaction tests; among them,
[0020] The first group of dynamic compaction tests had one number of compaction blows, and the compaction energy of each blow was the total compaction energy.
[0021] The second group of dynamic compaction tests involved three compaction blows, with each blow having an energy of one-third of the total compaction energy.
[0022] The third group of dynamic compaction tests involved three impacts. The impact energy of the first impact was three-sixths of the total impact energy, the impact energy of the second impact was two-sixths of the total impact energy, and the impact energy of the third impact was one-sixth of the total impact energy.
[0023] The fourth group of dynamic compaction tests involved three impacts. The impact energy of the first impact was one-sixth of the total impact energy, the impact energy of the second impact was two-sixths of the total impact energy, and the impact energy of the third impact was three-sixths of the total impact energy.
[0024] Furthermore, in each group of monitoring points, the number of monitoring points in multiple columns decreases by one in sequence along the direction away from the tamping point, and several monitoring points in each case are arranged at intervals from top to bottom in the vertical direction.
[0025] Furthermore, based on the initial soil data and the soil data after compaction at each monitoring point, the steps for calculating the reinforcement effect improvement rate at each monitoring point include:
[0026] If the soil data includes SPT blow counts, then for each monitoring point, the reinforcement improvement rate is calculated using the following formula:
[0027]
[0028] In the formula, W represents the reinforcement effect improvement rate, and SPT 初 SPT initial blow count for monitoring points 后 The standard penetration test (SPT) blow count after compaction at the monitoring point;
[0029] If the soil data includes penetration resistance, then for each monitoring point, the reinforcement improvement rate is calculated using the following formula:
[0030]
[0031] In the formula, CPT 初 CPT is the initial penetration resistance at the monitoring point. 后 The penetration resistance after tamping at the monitoring point;
[0032] If the soil data includes SPT blow count and penetration resistance, then for each monitoring point, the reinforcement improvement rate is calculated using the following formula:
[0033]
[0034] Furthermore, for each group of dynamic compaction tests, the steps for calculating the reinforcement analysis data for each monitoring point, based on the reinforcement improvement rate at each monitoring point, the acceleration data collected by the sensor unit at the monitoring point, and the pore water pressure data, include:
[0035] The following formula is used to calculate the improvement rate of vertical reinforcement along the depth direction at the monitoring point:
[0036]
[0037] In the formula, W n1i W represents the improvement rate of vertical reinforcement effect along the depth direction at the calculated monitoring points. 1i W is the calculated improvement rate of reinforcement effect at the monitoring points. 1(i-1) The reinforcement effect improvement rate of the monitoring point located above the calculated monitoring point along the depth direction;
[0038] The following formula is used to calculate the rate of increase in vertical acceleration along the depth direction at the monitoring point:
[0039]
[0040] In the formula, J n1i J is the rate of increase in vertical acceleration along the depth direction at the monitoring point. 1i For the acceleration data of the monitoring points, J 1(i-1) This refers to the acceleration data of the monitoring point located above the calculated monitoring point along the depth direction;
[0041] The vertical pore water pressure increase rate along the depth direction at the monitoring point is calculated using the following formula:
[0042]
[0043] In the formula, K n1i K is the rate of increase in vertical pore water pressure along the depth direction at the monitoring point. 1i For the pore water pressure data of the monitoring points, K 1(i-1) This refers to the pore water pressure data at monitoring points located above the calculated monitoring points along the depth direction;
[0044] The following formula is used to calculate the improvement rate of horizontal reinforcement effect at monitoring points along the direction away from the compaction point:
[0045]
[0046] In the formula, W n2i W represents the improvement rate of horizontal reinforcement effect at the monitoring points along the direction away from the tamping point. 2i W is the calculated improvement rate of reinforcement effect at the monitoring points. 2(i-1) The reinforcement effect improvement rate of monitoring points located behind the calculated monitoring points along the direction away from the tamping point;
[0047] The following formula is used to calculate the rate of increase in horizontal acceleration at the monitoring point along the direction away from the tamping point:
[0048]
[0049] In the formula, J n2i J is the rate of increase in horizontal acceleration at the monitoring point along the direction away from the tamping point. 2i For the acceleration data of the monitoring points, J 2(i-1) The acceleration data are for monitoring points located behind the calculated monitoring point along the direction away from the tamping point;
[0050] The following formula is used to calculate the rate of increase in horizontal pore water pressure at the monitoring point along the direction away from the tamping point:
[0051]
[0052] In the formula, K n2i K is the rate of increase in horizontal pore water pressure at the monitoring point along the direction away from the tamping point. 2i For the pore water pressure data of the monitoring points, K 2(i-1) This refers to the pore water pressure data at monitoring points located behind the calculated monitoring points along the direction away from the tamping point.
[0053] Furthermore, in the step of conducting multiple sets of dynamic compaction tests on the construction foundation, each set of dynamic compaction tests is performed several times.
[0054] Compared with the prior art, the beneficial effects of the present invention are as follows: by using field testing methods and analyzing vibration acceleration, pore water pressure changes, and soil data before and after dynamic compaction, the vertical reinforcement depth and horizontal reinforcement range of the dynamic compaction foundation treatment method in the foundation can be accurately determined. This is of great significance for evaluating the effect of dynamic compaction and reducing the impact of dynamic compaction construction on surrounding existing buildings and the environment. Attached Figure Description
[0055] Figure 1 This is a flowchart illustrating the steps of the method for determining the effective reinforcement depth and range of dynamic compaction according to the present invention.
[0056] Figure 2 A schematic diagram of multiple sets of monitoring points arranged around the compaction point in the method for determining the effective reinforcement depth and range of dynamic compaction in this invention;
[0057] Figure 3 This is a cross-sectional schematic diagram showing the arrangement of monitoring points around the compaction point in the method for determining the effective reinforcement depth and range of dynamic compaction according to the present invention. Detailed Implementation
[0058] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.
[0059] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.
[0060] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this invention, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.
[0061] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.
[0062] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed when in use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.
[0063] Please see Figure 1 , Figure 2 and Figure 3 , Figure 1 This is a flowchart illustrating the steps of the method for determining the effective reinforcement depth and range of dynamic compaction according to the present invention. Figure 2 This is a schematic diagram of a plan view showing multiple sets of monitoring points arranged around the compaction point in the method for determining the effective reinforcement depth and range of dynamic compaction in this invention. Figure 3 This is a cross-sectional schematic diagram showing the arrangement of monitoring points around the compaction point in the method for determining the effective reinforcement depth and range of dynamic compaction according to the present invention. A method for determining the effective reinforcement depth and range of dynamic compaction includes the following steps:
[0064] S1. Conduct multiple sets of dynamic compaction tests on the construction foundation. In the multiple sets of dynamic compaction tests, the total impact energy is a constant value. Change the number of impacts or the impact energy of each impact and make the number of impacts and the impact energy corresponding to each impact constitute a set of dynamic compaction tests.
[0065] S2. Before each set of dynamic compaction tests, multiple sets of monitoring points are set at intervals in the construction foundation around the compaction point selected for the dynamic compaction test. Each set of monitoring points includes multiple rows of monitoring points with different horizontal distances from the compaction point. Each row of monitoring points includes several monitoring points arranged at intervals along the vertical direction. A sensor unit is arranged on each monitoring point. The sensor unit includes an acceleration sensor and a pore water pressure sensor.
[0066] S3. Before each set of dynamic compaction tests, obtain the initial soil data for each monitoring point, and after each set of dynamic compaction tests, obtain the soil data after compaction for each monitoring point, as well as the acceleration data and pore water pressure data collected by the sensor unit. Based on the initial soil data and the soil data after compaction for each monitoring point, calculate the reinforcement effect improvement rate for each monitoring point. The soil data shall include at least one of the standard penetration test blow count or penetration resistance.
[0067] S4. For each group of dynamic compaction tests, based on the reinforcement effect improvement rate at each monitoring point, the acceleration data and pore water pressure data collected by the sensor unit at the monitoring point, calculate the reinforcement analysis data for each monitoring point. The reinforcement analysis data includes the vertical reinforcement effect improvement rate, vertical acceleration improvement rate, vertical pore water pressure improvement rate, the first ratio of the vertical reinforcement effect improvement rate to the vertical acceleration improvement rate, and the second ratio of the vertical reinforcement effect improvement rate to the vertical pore water pressure improvement rate at the monitoring point along the depth direction, as well as the horizontal reinforcement effect improvement rate, horizontal acceleration improvement rate, horizontal pore water pressure improvement rate, the third ratio of the horizontal reinforcement effect improvement rate to the horizontal acceleration improvement rate, and the fourth ratio of the horizontal reinforcement effect improvement rate to the horizontal pore water pressure improvement rate at the monitoring point along the direction away from the compaction point.
[0068] S5. Based on the reinforcement analysis data of monitoring points obtained from multiple sets of dynamic compaction tests, determine the effective reinforcement depth and horizontal range of dynamic compaction on the construction foundation.
[0069] In step S1 above, since different compaction schemes with different number of compaction blows and corresponding compaction energies for each blow will have different reinforcement effects and different ranges of influence on the construction foundation under the same total compaction energy, multiple sets of dynamic compaction tests are set in advance. The total compaction energy of the dynamic compaction test is a constant value. By changing the number of compaction blows or the compaction energy of each blow, the changed number of compaction blows and the corresponding compaction energy for each blow constitute a set of dynamic compaction tests. Thus, multiple sets of dynamic compaction tests are set to consider various compaction conditions and to reasonably evaluate the effective reinforcement depth and horizontal range of the construction foundation.
[0070] Furthermore, in step S1, the step of conducting multiple sets of dynamic compaction tests on the construction foundation involves conducting four sets of dynamic compaction tests on the construction foundation, namely, the first set of dynamic compaction tests, the second set of dynamic compaction tests, the third set of dynamic compaction tests, and the fourth set of dynamic compaction tests; wherein,
[0071] The first group of dynamic compaction tests had one number of compaction blows, and the compaction energy of each blow was the total compaction energy.
[0072] The second group of dynamic compaction tests involved three compaction blows, with each blow having an energy of one-third of the total compaction energy.
[0073] The third group of dynamic compaction tests involved three impacts. The impact energy of the first impact was three-sixths of the total impact energy, the impact energy of the second impact was two-sixths of the total impact energy, and the impact energy of the third impact was one-sixth of the total impact energy.
[0074] The fourth group of dynamic compaction tests involved three impacts. The impact energy of the first impact was one-sixth of the total impact energy, the impact energy of the second impact was two-sixths of the total impact energy, and the impact energy of the third impact was three-sixths of the total impact energy.
[0075] Four sets of dynamic compaction tests were designed to reasonably evaluate the effective reinforcement depth and horizontal range of the construction foundation.
[0076] In step S2 above, for each group of dynamic compaction tests, the first choice is to select compaction points on the construction foundation for the test. Generally, in large-area foundation treatment, the geological conditions of the construction foundation are similar, so it is not necessary to specifically select compaction points. Of course, based on the on-site investigation of the construction foundation or geological survey data, areas with representative geological conditions can be selected as compaction points on the construction foundation. After selecting the compaction points, in order to monitor the dynamic compaction data, multiple sets of monitoring points are set up in the construction foundation around the compaction points. Specifically, at least four sets of monitoring points are arranged, and four or more sets of monitoring points are equally spaced around the compaction points, so that the monitoring points are arranged in a ring on the plane to ensure that the monitoring points are in four directions around the compaction points. Figure 2 As shown. Furthermore, since the impact energy gradually decreases in both the horizontal and vertical directions during dynamic compaction, in order to save measurement costs and avoid wasting data, the number of monitoring points in each group of monitoring points decreases by one in the direction away from the compaction point, and several monitoring points in each case are arranged at intervals from top to bottom in the vertical direction. For example, in the horizontal direction from the compaction point, a row of monitoring points is buried at 1-meter intervals. A row of 7 monitoring points located 1 meter from the compaction point, with a 1-meter distance between adjacent points, has a monitoring depth of 7 meters when buried from top to bottom. A row of 6 monitoring points located 2 meters from the compaction point, with a 1-meter distance between adjacent points, has a monitoring depth of 6 meters when buried from top to bottom. A row of 5 monitoring points located 3 meters from the compaction point, with a 1-meter distance between adjacent points, has a monitoring depth of 5 meters when buried from top to bottom, and so on. A row of 1 monitoring point located 7 meters from the compaction point, buried from top to bottom, has a monitoring depth of 1 meter. Figure 3 As shown. Furthermore, when installing sensor units at each monitoring point, since the acceleration data measured by the accelerometer has a significant directionality, it is necessary to ensure that the accelerometers are aligned during installation. A guide frame can be used to prevent the accelerometers from deflecting when lowered into the monitoring point.
[0077] In step S3 above, to determine the reinforcement effect of the dynamic compaction test on the foundation soil, in-situ tests are conducted near the compaction points before and after the test to obtain the initial soil data and post-compaction soil data for each monitoring point. If different dynamic compaction tests are not far apart, in-situ tests can be conducted between two or three compaction points to obtain the initial soil data and post-compaction soil data for each monitoring point in the dynamic compaction test. After each set of dynamic compaction tests, acceleration data and pore water pressure data at each monitoring point are collected by the sensor unit within each monitoring point. Then, based on the initial soil data and post-compaction soil data for each monitoring point in the dynamic compaction test, the reinforcement improvement rate for each monitoring point can be calculated. The soil data can be SPT blow count, penetration resistance, or a combination of both. Further, the calculation process for the reinforcement improvement rate for each monitoring point is as follows:
[0078] If the soil data includes SPT blow counts, then for each monitoring point, the reinforcement improvement rate is calculated using the following formula:
[0079]
[0080] In the formula, W represents the reinforcement effect improvement rate, and SPT 初 SPT initial blow count for monitoring points 后 The standard penetration test (SPT) blow count after compaction at the monitoring point;
[0081] If the soil data includes penetration resistance, then for each monitoring point, the reinforcement improvement rate is calculated using the following formula:
[0082]
[0083] In the formula, CPT 初 CPT is the initial penetration resistance at the monitoring point. 后 The penetration resistance after tamping at the monitoring point;
[0084] If the soil data includes SPT blow count and penetration resistance, then for each monitoring point, the reinforcement improvement rate is calculated using the following formula:
[0085]
[0086] In addition, for each column of monitoring points, the average improvement rate of each column of monitoring points can be calculated based on the improvement rate of the reinforcement effect of several monitoring points in each column. This can be used as a reference data for preliminary judgment of the reinforcement effect of dynamic compaction. Generally, it is considered that an improvement rate of more than 50% is good, 30-50% is good, and less than 30% is poor.
[0087] Furthermore, to eliminate random errors from a single test, in step S1, during the process of conducting multiple sets of dynamic compaction tests on the construction foundation, each set of dynamic compaction tests is performed several times. Preferably, each set of dynamic compaction tests is performed three times. Identical dynamic compaction tests should be conducted in the same area of the construction foundation whenever possible.
[0088] Since each set of dynamic compaction tests is conducted several times, in step S3, for each monitoring point in each set of dynamic compaction tests, several initial soil data, several post-compaction soil data, several acceleration data, and several pore water pressure data are obtained. Therefore, for each monitoring point in each set of dynamic compaction tests, the average values of the initial soil data, the post-compaction soil data, the acceleration data, and the pore water pressure data are calculated respectively. The calculated average value of the initial soil data is used as the initial soil data of the monitoring point, the calculated average value of the post-compaction soil data is used as the post-compaction soil data of the monitoring point, the calculated average value of the acceleration data is used as the acceleration data of the monitoring point, and the calculated average value of the pore water pressure data is used as the pore water pressure data of the monitoring point for subsequent calculations.
[0089] In step S4 above, the improvement rate of vertical reinforcement effect along the depth direction of the monitoring point is calculated using the following formula:
[0090]
[0091] In the formula, W n1i W represents the improvement rate of vertical reinforcement effect along the depth direction at the calculated monitoring points. 1i W is the calculated improvement rate of reinforcement effect at the monitoring points. 1(i-1) The reinforcement effect improvement rate of the monitoring point located above the calculated monitoring point along the depth direction;
[0092] The following formula is used to calculate the rate of increase in vertical acceleration along the depth direction at the monitoring point:
[0093]
[0094] In the formula, J n1i J is the rate of increase in vertical acceleration along the depth direction at the monitoring point. 1i For the acceleration data of the monitoring points, J 1(i-1)This refers to the acceleration data of the monitoring point located above the calculated monitoring point along the depth direction;
[0095] The vertical pore water pressure increase rate along the depth direction at the monitoring point is calculated using the following formula:
[0096]
[0097] In the formula, K n1i K is the rate of increase in vertical pore water pressure along the depth direction at the monitoring point. 1i For the pore water pressure data of the monitoring points, K 1(i-1) This refers to the pore water pressure data at monitoring points located above the calculated monitoring points along the depth direction;
[0098] The following formula is used to calculate the improvement rate of horizontal reinforcement effect at monitoring points along the direction away from the compaction point:
[0099]
[0100] In the formula, W n2i W represents the improvement rate of horizontal reinforcement effect at the monitoring points along the direction away from the tamping point. 2i W is the calculated improvement rate of reinforcement effect at the monitoring points. 2(i-1) The reinforcement effect improvement rate of monitoring points located behind the calculated monitoring points along the direction away from the tamping point;
[0101] The following formula is used to calculate the rate of increase in horizontal acceleration at the monitoring point along the direction away from the tamping point:
[0102]
[0103] In the formula, J n2i J is the rate of increase in horizontal acceleration at the monitoring point along the direction away from the tamping point. 2i For the acceleration data of the monitoring points, J 2(i-1) The acceleration data are for monitoring points located behind the calculated monitoring point along the direction away from the tamping point;
[0104] The following formula is used to calculate the rate of increase in horizontal pore water pressure at the monitoring point along the direction away from the tamping point:
[0105]
[0106] In the formula, K n2i K is the rate of increase in horizontal pore water pressure at the monitoring point along the direction away from the tamping point. 2i For the pore water pressure data of the monitoring points, K 2(i-1) This refers to the pore water pressure data at monitoring points located behind the calculated monitoring points along the direction away from the tamping point.
[0107] For each monitoring point, the first ratio M of the improvement rate of vertical reinforcement effect to the improvement rate of vertical acceleration can be obtained from the above calculation results. n1i for:
[0108]
[0109] The second ratio L of the improvement rate of vertical reinforcement effect to the improvement rate of vertical pore water pressure n1i for:
[0110]
[0111] The third ratio of the improvement rate of horizontal reinforcement effect to the improvement rate of horizontal acceleration is:
[0112]
[0113] The fourth ratio of the improvement rate of horizontal reinforcement effect to the improvement rate of horizontal pore water pressure is:
[0114]
[0115] Based on the above calculation process, the multiple monitoring points of each group of dynamic compaction tests are calculated one by one, so as to obtain the reinforcement analysis data of each monitoring point in each group of dynamic compaction tests.
[0116] Step S5 includes:
[0117] S51. In multiple sets of dynamic compaction tests, the monitoring points with the same relative position as the compaction point are taken as the same monitoring point. The multiple reinforcement analysis data of the monitoring point are compared to obtain the maximum vertical acceleration increase rate, the maximum vertical pore water pressure increase rate, the maximum horizontal acceleration increase rate, the maximum horizontal pore water pressure increase rate, the maximum first ratio, the maximum second ratio, the maximum third ratio, and the maximum fourth ratio corresponding to the monitoring point.
[0118] S52. Select monitoring points in each column of monitoring points in order from top to bottom, take the first monitoring point that meets the first selection condition as the first target monitoring point, and then obtain the burial depth of the first target monitoring point in the construction foundation to obtain multiple burial depths. The first selection condition is that the maximum first ratio and the maximum second ratio of the monitoring point are both less than the preset first threshold, and the maximum vertical acceleration increase rate and the maximum vertical pore water pressure increase rate of the monitoring point are both less than the preset second threshold.
[0119] S53. Compare the multiple buried depths obtained, and take the largest buried depth as the effective reinforcement depth of dynamic compaction on the construction foundation.
[0120] S54. For each group of monitoring points, several monitoring points with the same burial depth are taken as the same row of monitoring points to obtain several rows of monitoring points. In each row of monitoring points, monitoring points are selected in the order of being furthest from the tamping point. The first monitoring point that meets the second selection condition is taken as the second target monitoring point. Then, the horizontal distance between the second target monitoring point and the tamping point is obtained to obtain multiple horizontal distances. The second selection condition is that the maximum third ratio and the maximum fourth ratio of the monitoring point are both less than the preset first threshold, and the maximum horizontal acceleration increase rate and the maximum horizontal pore water pressure increase rate of the monitoring point are both less than the preset second threshold.
[0121] S55. Compare the multiple horizontal distances obtained, and take the largest horizontal distance as the effective horizontal reinforcement range of dynamic compaction on the construction foundation.
[0122] In step S51 above, the distance between the compaction point and the monitoring point in each group of dynamic compaction tests is used as the judgment criterion. In multiple groups of dynamic compaction tests, the monitoring points at the same location as the compaction point in the dynamic compaction test are regarded as the same monitoring point. Then, each monitoring point will have multiple reinforcement analysis data. Therefore, the multiple reinforcement analysis data of the monitoring point are compared to obtain the maximum vertical acceleration improvement rate J corresponding to the monitoring point. n1i-max Maximum vertical pore water pressure increase rate K n1i-max The rate of increase in maximum horizontal acceleration J n2i-max Maximum horizontal pore water pressure increase rate K n2i-max The largest first ratio M n1i-max The second largest ratio L n1i-max The largest third ratio M n2i-max The ratio of the largest fourth value L n2i-max , to be used as an evaluation index for the analysis of the depth and horizontal range of dynamic compaction reinforcement.
[0123] In steps S52 and S53 above, for each column of monitoring points in each group of monitoring points, one monitoring point is selected from several monitoring points in a top-to-bottom order. Then, it is determined whether the selected monitoring point meets the first selection condition, that is, whether the maximum first ratio and the maximum second ratio of the selected monitoring point are both less than a preset first threshold, and whether the maximum vertical acceleration increase rate and the maximum vertical pore water pressure increase rate of the selected monitoring point are both less than a preset second threshold. If the determination is yes, it means that the selected monitoring point meets the first selection condition. The first monitoring point in each column of monitoring points that meets the first selection condition is recorded as the first target monitoring point. The preset first threshold can be 0.1, and the preset second threshold can be 0.05. Since the evaluation indicators obtained during the dynamic compaction process generally decrease gradually along the depth, after obtaining the first target monitoring point, it is not necessary to judge the remaining monitoring points in each column. Then, the embedment depth of the first target monitoring point in the construction foundation is obtained. Since a first target monitoring point is selected in each column of monitoring points, and each first target monitoring point corresponds to its embedment depth, multiple embedment depths are obtained. Finally, the multiple embedment depths are compared, and the largest embedment depth is taken as the effective reinforcement depth for dynamic compaction on the construction foundation.
[0124] In steps S54 and S55 above, each group of monitoring points includes multiple columns of monitoring points, and each column of monitoring points includes several monitoring points spaced apart from top to bottom. Therefore, there are multiple monitoring points at the same burial depth of the construction foundation, and these multiple monitoring points are in the same row, resulting in several rows of monitoring points. For each row of monitoring points in each group, one monitoring point is selected from the multiple monitoring points in the order away from the compaction point. Then, it is determined whether the selected monitoring point meets the second selection condition, that is, whether the maximum third ratio and the maximum fourth ratio of the selected monitoring point are both less than the preset first threshold, and whether the maximum horizontal acceleration increase rate and the maximum horizontal pore water pressure increase rate of the selected monitoring point are both less than the preset second threshold. If the determination is yes, it means that the selected monitoring point meets the second selection condition. The first monitoring point in each row that meets the second selection condition is recorded as the second target monitoring point. The preset first threshold can be 0.1, and the preset second threshold can be 0.05. Since the evaluation indicators obtained during dynamic compaction generally decrease gradually away from the compaction point, it is unnecessary to evaluate the remaining monitoring points in each row after obtaining the second target monitoring point. Then, the horizontal distance between the second target monitoring point and the compaction point is obtained. Because a second target monitoring point is selected in each row, and each second target monitoring point corresponds to a horizontal distance from its respective compaction point, multiple horizontal distances are obtained. Finally, these multiple horizontal distances are compared, and the largest horizontal distance is taken as the effective horizontal reinforcement range for dynamic compaction on the construction foundation. Furthermore, when the effective reinforcement depth and horizontal range for dynamic compaction on the construction foundation are determined, the same effective reinforcement depth and horizontal range can be directly adopted when encountering foundations with the same geological conditions in other projects.
[0125] Compared with the prior art, the beneficial effects of the present invention are as follows: by using field testing methods and analyzing vibration acceleration, pore water pressure changes, and soil data before and after dynamic compaction, the vertical reinforcement depth and horizontal reinforcement range of the dynamic compaction foundation treatment method in the foundation can be accurately determined. This is of great significance for evaluating the effect of dynamic compaction and reducing the impact of dynamic compaction construction on surrounding existing buildings and the environment.
[0126] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Therefore, any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.
Claims
1. A method for determining the effective reinforcement depth and range of dynamic compaction, characterized in that, Includes the following steps: Multiple sets of dynamic compaction tests were carried out on the construction foundation. In the multiple sets of dynamic compaction tests, the total compaction energy was a constant value. The number of compaction blows or the compaction energy of each compaction blow were varied so that the number of compaction blows and the compaction energy corresponding to each compaction blow constituted a set of dynamic compaction tests. Before each set of dynamic compaction tests, multiple sets of monitoring points are set at intervals in the construction foundation around the compaction point selected for the dynamic compaction test. Each set of monitoring points includes multiple rows of monitoring points with different horizontal distances from the compaction point. Each row of monitoring points includes several monitoring points arranged at intervals along the vertical direction. A sensor unit is arranged on each monitoring point. The sensor unit includes an acceleration sensor and a pore water pressure sensor. Before each set of dynamic compaction tests, initial soil data for each monitoring point is acquired, and after each set of dynamic compaction tests, soil data after compaction at each monitoring point is acquired, as well as acceleration data and pore water pressure data collected by the sensor unit. Based on the initial soil data and soil data after compaction at each monitoring point, the reinforcement effect improvement rate of each monitoring point is calculated. The soil data includes at least one of standard penetration test blow count or penetration resistance. For each group of dynamic compaction tests, based on the improvement rate of the reinforcement effect at each monitoring point, the acceleration data and pore water pressure data collected by the sensor unit at the monitoring point, the reinforcement analysis data for each monitoring point is calculated. The reinforcement analysis data includes the improvement rate of the vertical reinforcement effect, the improvement rate of the vertical acceleration, the improvement rate of the vertical pore water pressure, the first ratio of the improvement rate of the vertical reinforcement effect to the improvement rate of the vertical acceleration, and the second ratio of the improvement rate of the vertical reinforcement effect to the improvement rate of the vertical pore water pressure along the depth direction of the monitoring point; and the improvement rate of the horizontal reinforcement effect, the improvement rate of the horizontal acceleration, the improvement rate of the horizontal pore water pressure, the third ratio of the improvement rate of the horizontal reinforcement effect to the improvement rate of the horizontal acceleration, and the fourth ratio of the improvement rate of the horizontal reinforcement effect to the improvement rate of the horizontal pore water pressure along the direction away from the compaction point. Based on the reinforcement analysis data of monitoring points obtained from multiple sets of dynamic compaction tests, the effective reinforcement depth and horizontal range of dynamic compaction on the construction foundation were determined. The steps for determining the effective reinforcement depth and horizontal range of dynamic compaction on the construction foundation based on the reinforcement analysis data of monitoring points obtained from multiple sets of dynamic compaction tests include: Monitoring points with the same relative position to the compaction point in multiple sets of dynamic compaction tests are taken as the same monitoring point. Multiple reinforcement analysis data of the monitoring point are compared to obtain the maximum vertical acceleration increase rate, maximum vertical pore water pressure increase rate, maximum horizontal acceleration increase rate, maximum horizontal pore water pressure increase rate, maximum first ratio, maximum second ratio, maximum third ratio and maximum fourth ratio corresponding to the monitoring point. In each column of monitoring points, monitoring points are selected in order from top to bottom. The first monitoring point that meets the first selection condition is taken as the first target monitoring point. Then, the burial depth of the first target monitoring point in the construction foundation is obtained, resulting in multiple burial depths. The first selection condition is that the maximum first ratio and the maximum second ratio of the monitoring point are both less than the preset first threshold, and the maximum vertical acceleration increase rate and the maximum vertical pore water pressure increase rate of the monitoring point are both less than the preset second threshold. The multiple burial depths obtained were compared, and the largest burial depth was taken as the effective reinforcement depth of dynamic compaction on the construction foundation. For each group of monitoring points, several monitoring points with the same burial depth are grouped into the same row of monitoring points to obtain several rows of monitoring points. Monitoring points are selected in each row of monitoring points in the order of being furthest from the compaction point. The first monitoring point that meets the second selection condition is taken as the second target monitoring point. Then, the horizontal distance between the second target monitoring point and the compaction point is obtained to obtain multiple horizontal distances. The second selection condition is that the maximum third ratio and the maximum fourth ratio of the monitoring point are both less than the preset first threshold, and the maximum horizontal acceleration increase rate and the maximum horizontal pore water pressure increase rate of the monitoring point are both less than the preset second threshold. The obtained horizontal distances are compared, and the largest horizontal distance is taken as the effective horizontal reinforcement range of dynamic compaction on the construction foundation.
2. The method for determining the effective reinforcement depth and range of dynamic compaction according to claim 1, characterized in that, In the step of conducting multiple sets of dynamic compaction tests on the construction foundation, four sets of dynamic compaction tests were carried out on the construction foundation: the first set of dynamic compaction tests, the second set of dynamic compaction tests, the third set of dynamic compaction tests, and the fourth set of dynamic compaction tests. The first group of dynamic compaction tests had one number of compaction blows, and the compaction energy of each blow was the total compaction energy. The second group of dynamic compaction tests involved three compaction blows, with each blow having an energy of one-third of the total compaction energy. The third group of dynamic compaction tests involved three impacts. The impact energy of the first impact was three-sixths of the total impact energy, the impact energy of the second impact was two-sixths of the total impact energy, and the impact energy of the third impact was one-sixth of the total impact energy. The fourth group of dynamic compaction tests involved three impacts. The impact energy of the first impact was one-sixth of the total impact energy, the impact energy of the second impact was two-sixths of the total impact energy, and the impact energy of the third impact was three-sixths of the total impact energy.
3. The method for determining the effective reinforcement depth and range of dynamic compaction according to claim 1, characterized in that, In each group of monitoring points, the number of monitoring points in multiple columns decreases by one in sequence along the direction away from the tamping point, and several monitoring points in each case are arranged at intervals from top to bottom in the vertical direction.
4. The method for determining the effective reinforcement depth and range of dynamic compaction according to claim 1, characterized in that, The step of calculating the reinforcement effect improvement rate for each monitoring point based on the initial soil data and the soil data after compaction includes: If the soil data includes SPT blow counts, then for each monitoring point, the reinforcement improvement rate is calculated using the following formula: ； In the formula, To improve the reinforcement effect, The initial standard penetration test (SPT) blow count at the monitoring point. The standard penetration test (SPT) blow count after compaction at the monitoring point; If the soil data includes penetration resistance, then for each monitoring point, the reinforcement improvement rate is calculated using the following formula: ； In the formula, The initial penetration resistance at the monitoring point, The penetration resistance after tamping at the monitoring point; If the soil data includes SPT blow count and penetration resistance, then for each monitoring point, the reinforcement improvement rate is calculated using the following formula: 。 5. The method for determining the effective reinforcement depth and range of dynamic compaction according to claim 1, characterized in that, The steps for calculating the reinforcement analysis data for each monitoring point for each group of dynamic compaction tests, based on the reinforcement effect improvement rate at each monitoring point, the acceleration data collected by the sensor unit at the monitoring point, and the pore water pressure data, include: The following formula is used to calculate the improvement rate of vertical reinforcement along the depth direction at the monitoring point: ； In the formula, The calculated improvement rate of vertical reinforcement effect along the depth direction at the monitoring point. The calculation shows the improvement rate of reinforcement effect at the monitoring points. The reinforcement effect improvement rate of the monitoring point located above the calculated monitoring point along the depth direction; The following formula is used to calculate the rate of increase in vertical acceleration along the depth direction at the monitoring point: ； In the formula, The calculated rate of increase in vertical acceleration along the depth direction at the monitoring point. For the acceleration data of the monitoring points, This refers to the acceleration data of the monitoring point located above the calculated monitoring point along the depth direction; The vertical pore water pressure increase rate along the depth direction at the monitoring point is calculated using the following formula: ； In the formula, The vertical pore water pressure increase rate along the depth direction at the monitoring point is calculated. For the calculation of pore water pressure data at the monitoring points, This refers to the pore water pressure data at monitoring points located above the calculated monitoring points along the depth direction; The following formula is used to calculate the improvement rate of horizontal reinforcement effect at monitoring points along the direction away from the compaction point: ； In the formula, The calculated improvement rate of horizontal reinforcement effect at monitoring points along the direction away from the tamping point. The calculation shows the improvement rate of reinforcement effect at the monitoring points. The reinforcement effect improvement rate of monitoring points located behind the calculated monitoring points along the direction away from the tamping point; The following formula is used to calculate the rate of increase in horizontal acceleration at the monitoring point along the direction away from the tamping point: ； In the formula, The calculated rate of increase in horizontal acceleration at the monitoring point along the direction away from the tamping point. For the acceleration data of the monitoring points, The acceleration data are for monitoring points located behind the calculated monitoring point along the direction away from the tamping point; The following formula is used to calculate the rate of increase in horizontal pore water pressure at the monitoring point along the direction away from the tamping point: ； In the formula, The calculated rate of increase in horizontal pore water pressure at the monitoring point along the direction away from the tamping point is given. For the calculation of pore water pressure data at the monitoring points, This refers to the pore water pressure data at monitoring points located behind the calculated monitoring points along the direction away from the tamping point.
6. The method for determining the effective reinforcement depth and range of dynamic compaction according to claim 1, characterized in that, In the step of conducting multiple sets of dynamic compaction tests on the construction foundation, each set of dynamic compaction tests is performed several times.