JP2020197087A - Lateral pressure evaluation method of retaining wall, and lateral pressure evaluation device - Google Patents

Abstract

To provide a lateral pressure evaluation method of a retaining wall capable of easily obtaining realistic depth distribution of lateral pressure at the excavation side at each excavation stage, and a lateral pressure evaluation device.SOLUTION: The lateral pressure evaluation method of a retaining wall is a method for evaluating the lateral pressure at the excavation side, which acts on a retaining wall 3 when excavating the ground with predetermined excavation width B, depth L at a depth h. The excavation side lateral pressure is found at each excavation stage by apply a vertical stress σz at a position separated away by a predetermined distance from a retaining wall 3 at the excavation side to the formula of Rankine-Resal method. The vertical stress σz is a vertical stress at a predetermined depth z from the excavation bottom face 2 when the excavated soil mass 1 excavated and discharged, which acts on the excavation bottom face 2 as an unloading weight. It is preferable to subtract the unloading stress due to the stress solution of Steinbrenner from one-dimensional vertical soil cover pressure before excavation. The ground is alluvial ground, and the vertical stress σz is preferably vertical stress at a position 0.1 times the excavation width B from the retaining wall 3 at the excavation side.SELECTED DRAWING: Figure 1

Description

The present invention relates to, for example, a lateral pressure evaluation method and a lateral pressure evaluation device for a retaining wall in an alluvial ground.

Conventionally, the stress and deformation of the retaining wall are calculated by appropriately evaluating the load and resistance acting on the retaining wall and balancing the forces at each next excavation stage. The excavation side pressure, which is the resistance of the excavation side, is affected by the unloading of excavated soil mass and the deformation of the retaining wall, and exhibits more complicated mechanical behavior than the back side earth pressure. The Architectural Institute of Japan guidelines recommend that one-dimensional unloading be assumed for easy and safe evaluation, and that the excavation side pressure be calculated from the root cutting floor of each next excavation.

However, it has been pointed out that the deformation calculation of the retaining wall by this method tends to overestimate the displacement near the flooring at the time of final excavation. As shown in FIG. 5, in the ground mainly composed of soft alluvial clay, the displacement of the retaining wall at the time of the final excavation when the excavation width: B = 22.8 m and the depth: L = 32.0 m are excavated at a depth of 13 m. Fig. 6 shows the measured values and the calculated values (AIJ guidelines) according to the recommended method of the Architectural Institute of Japan guidelines. Since the calculated value shows a considerably larger value than the measured value, it is suggested that the recommended method of the Architectural Institute of Japan guideline underestimates the side pressure on the excavation side and may not necessarily match the actual phenomenon.

As a monitoring technique for confirming the deformation of the structure at the time of excavating the ground for the retaining work, for example, the one described in Patent Document 1 is known.

Japanese Unexamined Patent Publication No. 8-151633

For this reason, there has been a demand for a method that can easily obtain a more realistic depth distribution of excavation side pressure for each next excavation stage in the alluvial ground retaining wall.

The present invention has been made in view of the above, and provides a lateral pressure evaluation method and a lateral pressure evaluation device for a retaining wall, which can easily obtain a more realistic depth distribution of excavation side pressure for each next excavation stage. The purpose is to do.

In order to solve the above-mentioned problems and achieve the object, the method for evaluating the lateral pressure of the retaining wall according to the present invention is the excavation side pressure acting on the retaining wall when the ground is excavated at a predetermined excavation width, depth and depth. It is a method to evaluate the method, and to obtain the excavation side pressure at each next excavation stage by applying the normal stress at a position separated by a predetermined distance from the retaining wall to the excavation side to the calculation formula by the Rankin-Lesard method. It is a feature.

Further, in the other method for evaluating the lateral pressure of the retaining wall according to the present invention, in the above-described invention, the normal stress is applied from the bottom surface of the root cutting when the excavated soil mass excavated and discharged is acted on the bottom surface of the root cutting as a deload. It is a normal stress at a predetermined depth, and is characterized in that it is obtained by subtracting the unloading stress due to the stress solution of Steinbrener from the one-dimensional vertical soil cover pressure before excavation.

Further, in the other method for evaluating the lateral pressure of the retaining wall according to the present invention, in the above-mentioned invention, the ground is alluvial ground, and the normal stress is separated from the retaining wall to the excavation side by a distance of 0.1 times the excavation width. It is characterized by being a normal stress at the position.

Further, the lateral pressure evaluation device for the retaining wall according to the present invention is an apparatus for evaluating the excavation side pressure acting on the retaining wall when the ground is excavated with a predetermined excavation width, depth and depth, and is the Rankin-Rezal method. It is characterized by applying the normal stress at a position separated by a predetermined distance from the retaining wall to the excavation side to obtain the excavation side pressure at each next excavation stage.

Further, in the other lateral pressure evaluation device for the retaining wall according to the present invention, in the above-described invention, the normal stress is applied from the bottom surface of the root cutting when the excavated soil mass excavated and discharged is acted on the bottom surface of the root cutting as a deload. It is a normal stress at a predetermined depth, and is characterized in that it is obtained by subtracting the unloading stress due to the stress solution of Steinbrener from the one-dimensional vertical soil cover pressure before excavation.

Further, in the other lateral pressure evaluation device for the retaining wall according to the present invention, in the above-mentioned invention, the ground is alluvial ground, and the normal stress is separated from the retaining wall to the excavation side by a distance of 0.1 times the excavation width. It is characterized by being a normal stress at the position.

According to the method for evaluating the lateral pressure of the retaining wall according to the present invention, it is a method for evaluating the lateral pressure acting on the retaining wall when the ground is excavated at a predetermined excavation width, depth, and depth, and is the Rankin-Rezal method. Since the vertical stress at a position separated from the retaining wall by a predetermined distance from the retaining wall is applied to obtain the excavation side pressure at each next excavation stage, the excavation side is more realistic for each next excavation stage. It has the effect that the depth distribution of lateral pressure can be easily obtained.

Further, according to another method for evaluating the lateral pressure of the retaining wall according to the present invention, the normal stress is a predetermined depth from the bottom surface of the root cutting when the excavated soil mass excavated and discharged is acted on the bottom surface of the root cutting as a deload. Since the normal stress is obtained by subtracting the unloading stress due to the stress solution of Steinbrenner from the one-dimensional vertical soil cover pressure before excavation, the normal stress used for the evaluation of the excavation side pressure can be easily obtained. It works.

Further, according to another method for evaluating the lateral pressure of the retaining wall according to the present invention, the ground is an alluvial ground, and the normal stress is vertical at a position separated from the retaining wall by 0.1 times the excavation width on the excavation side. Since it is a stress, it has the effect of improving the accuracy of evaluation.

Further, according to the lateral pressure evaluation device for the retaining wall according to the present invention, it is an apparatus for evaluating the excavation side pressure acting on the retaining wall when the ground is excavated with a predetermined excavation width, depth, and depth. Since the normal stress at a position separated from the retaining wall by a predetermined distance from the retaining wall is applied to the calculation formula by the Rezal method to obtain the excavation side pressure at each next excavation stage, it is more realistic for each next excavation stage. It has the effect that the depth distribution of the excavation side pressure can be easily obtained.

Further, according to another lateral pressure evaluation device for the retaining wall according to the present invention, the normal stress is a predetermined depth from the root cutting bottom surface when the excavated soil mass excavated and discharged is acted on the root cutting bottom surface as a deload. Since the normal stress is obtained by subtracting the unloading stress due to the stress solution of Steinbrenner from the one-dimensional vertical soil cover pressure before excavation, the normal stress used for the evaluation of the excavation side pressure can be easily obtained. It works.

Further, according to another lateral pressure evaluation device for the retaining wall according to the present invention, the ground is an alluvial ground, and the normal stress is vertical at a position separated from the retaining wall by 0.1 times the excavation width on the excavation side. Since it is a stress, it has the effect of improving the accuracy of evaluation.

FIG. 1 is a diagram showing a calculation model of vertical unloading stress by the stress solution of Steinbrener in the present invention. FIG. 2 is a diagram showing actual measurement values and calculated values (examples) of the displacement of the retaining wall at the time of final excavation. FIG. 3 is a diagram showing a correction coefficient (α) of the vertical unloading stress at a position 0.1B away from the retaining wall. FIG. 4 is a diagram showing a correction coefficient (1-α) of the vertical unloading stress at a position 0.1B away from the retaining wall. FIG. 5 is a diagram showing an example of excavating the ground mainly composed of conventional soft alluvial clay, where (1) is a plan view and (2) is a cross-sectional view. FIG. 6 is a diagram showing actual measurement values and calculated values of the displacement of the retaining wall at the time of the conventional final excavation.

Hereinafter, a method for evaluating the lateral pressure of the retaining wall and an embodiment of the lateral pressure evaluation device according to the present invention will be described in detail with reference to the drawings. The present invention is not limited to this embodiment.

<Method of evaluating lateral pressure on the retaining wall>
First, an embodiment of the method for evaluating the lateral pressure of the retaining wall of the present invention will be described.
The method for evaluating the lateral pressure of the retaining wall according to the present embodiment is a method for evaluating the lateral pressure acting on the retaining wall when the ground is excavated at a predetermined excavation width, depth, and depth, and is the Rankin-Rezal method. The vertical stress at a position separated from the retaining wall by a predetermined distance from the retaining wall is applied to the calculation formula according to the above to obtain the excavation side pressure at each next excavation stage. The alluvial ground is assumed to be excavated.

A calculation model to which this embodiment is applied is shown in FIG. As shown in this figure, the excavated soil mass 1 (depth L, excavation width B, excavation depth h) to be discharged is acted on the root cutting bottom surface 2 as a deload. The vertical stress σ _z (= γ _tz −p _ww ) at a position separated by a horizontal distance of 0.1 B from the retaining wall 3 and at a depth z from the root cutting bottom is the one-dimensional vertical soil _cover pressure σ _z0 before excavation. It is obtained by subtracting the unloading stress Δσ _{z (e)} from the stress solution of the horizontal blender from (= γ _t (z + h) -p _ww ). Here, γ _t : wet unit volume weight of the soil, p _ww : water pressure on the excavation side at a depth z from the root cutting bottom.

For the calculation of the excavation side pressure P _p acting on the retaining wall, a method based on the active soil pressure obtained by the Rankin-Rezal method (hereinafter referred to as the Rankin-Rezal method) is used in accordance with the guidelines of the Architectural Institute of Japan.

(Side pressure P _p according to AIJ guideline)

Here, c: the adhesive force of the soil, φ: the internal friction angle of the soil. The following equation can be obtained by using the normal stress that incorporates the unloading stress from the stress solution of Steinbrener in the calculation by the Rankin-Lesard method.

(Lateral pressure _{P p} 'according to the present invention)

Here, σ _z : vertical soil cover pressure at a depth z from the root cutting bottom, and Δσ _{z (e)} : unloading stress due to excavated soil mass. The following equation is obtained by modifying the equation (3).

Here, the following equation can be obtained by rearranging equation (4) with Δσ _{z (e)} / Δσ _{z (1D)} = α.

<Verification of the effect of the present invention>
Under the ground and construction conditions shown in Fig. 5, the deformation was calculated by trial and error using Eq. (6) for the calculation of the excavation side pressure and the elasto-plastic method (beam / spring model) for the calculation method of the deformation occurring on the retaining wall. It was. The calculation result is shown in FIG.

As shown in this figure, the displacement of the retaining wall at the time of final excavation is calculated by adopting the unloading stress at each next excavation stage at a position 2 m (about 0.1B) away from the retaining wall in the calculation of the excavation side pressure. The result that the value is close to the measured value was obtained.

The α used in Eq. (6), which is a modification of the Rankin-Lesal method, can be read from, for example, a chart as shown in FIG. The vertical axis in FIG. 3 is the ratio of the depth z from the root cutting bottom to the excavation width B, and the horizontal axis is the unloading stress Δσ _{z (e)} and the one-dimensional unloading stress Δσ _{z (1D )} due to the stress solution of Steinbrenner. ₎ Ratio (= α: correction coefficient).

FIG. 4 is a chart in which the vertical unloading stress at a position separated from the retaining wall by 0.1 B can be easily read. For practical use, the chart shown in FIG. 4 is created in advance, 1-α corresponding to the correction coefficient of equation (6) is read from this chart, and the excavation side pressure is calculated using equation (6) modified by the Rankin-Rezal method. By calculating, the depth distribution of the excavation side pressure that matches the reality is set.

According to the present embodiment, in the design calculation when constructing the alluvial ground, a chart for obtaining the correction coefficient 1-α of the vertical unloading stress at a position 0.1B away from the alluvial wall (Fig.) By using Eq. (6), which is a modification of the Rankin-Rezal method, together with (see 4), it is possible to easily obtain a more realistic depth distribution of the excavation side pressure for each next excavation stage. Since it is possible to set the depth distribution of the excavation side pressure according to the reality, the calculation accuracy of the deformation that occurs in the retaining wall during the final excavation is improved.

In the above embodiment, the case where the normal stress at a position separated from the retaining wall by 0.1B on the excavation side is used as an example has been described, but the distance of the present invention is not limited to this. For example, a distance that can approximate the measured value of the displacement of the retaining wall at the time of final excavation may be examined in advance according to the characteristics of the ground, and the normal stress at a position separated by that distance may be used. Even in this way, the same effects as described above can be obtained.

<Side pressure evaluation device for retaining wall>
Next, an embodiment of the lateral pressure evaluation device for the retaining wall of the present invention will be described.
The lateral pressure evaluation device for the retaining wall according to the present embodiment embodies the above-mentioned lateral pressure evaluation method for the retaining wall as an apparatus. For example, a computer having a CPU, a memory for storing data, and data are input. It consists of a keyboard and a display that outputs data. The computer executes the calculation of the above equation (6) based on the ground / construction condition data input through the memory, keyboard, etc., and the data of FIGS. 3 and 4, and outputs the result to the display or the like. , It is possible to easily grasp the depth distribution of the excavation side pressure more realistically for each next excavation stage.

As described above, according to the method for evaluating the lateral pressure of the retaining wall according to the present invention, it is a method for evaluating the excavation side pressure acting on the retaining wall when the ground is excavated at a predetermined excavation width, depth, and depth. Then, the normal stress at a position separated by a predetermined distance from the retaining wall to the excavation side is applied to the calculation formula by the Rankin-Lesard method to obtain the excavation side pressure at each next excavation stage. The depth distribution of the excavation side pressure can be easily obtained according to the actual situation.

Further, according to another method for evaluating the lateral pressure of the retaining wall according to the present invention, the normal stress is a predetermined depth from the bottom surface of the root cutting when the excavated soil mass excavated and discharged is acted on the bottom surface of the root cutting as a deload. Since the normal stress is obtained by subtracting the unloading stress due to the stress solution of Steinbrenner from the one-dimensional vertical soil cover pressure before excavation, the normal stress used for evaluating the excavation side pressure can be easily obtained.

Further, according to another method for evaluating the lateral pressure of the retaining wall according to the present invention, the ground is an alluvial ground, and the normal stress is vertical at a position separated from the retaining wall by 0.1 times the excavation width on the excavation side. Since it is a stress, the accuracy of evaluation can be improved.

Further, according to the lateral pressure evaluation device for the retaining wall according to the present invention, it is an apparatus for evaluating the excavation side pressure acting on the retaining wall when the ground is excavated with a predetermined excavation width, depth, and depth. Since the normal stress at a position separated from the retaining wall by a predetermined distance from the retaining wall is applied to the calculation formula by the Rezal method to obtain the excavation side pressure at each next excavation stage, it is more realistic for each next excavation stage. The depth distribution of the excavation side pressure can be easily obtained.

Further, according to another lateral pressure evaluation device for the retaining wall according to the present invention, the normal stress is a predetermined depth from the root cutting bottom surface when the excavated soil mass excavated and discharged is acted on the root cutting bottom surface as a deload. Since the normal stress is obtained by subtracting the unloading stress due to the stress solution of Steinbrenner from the one-dimensional vertical soil cover pressure before excavation, the normal stress used for evaluating the excavation side pressure can be easily obtained.

Further, according to another lateral pressure evaluation device for the retaining wall according to the present invention, the ground is an alluvial ground, and the normal stress is vertical at a position separated from the retaining wall by 0.1 times the excavation width on the excavation side. Since it is a stress, the accuracy of evaluation can be improved.

As described above, the lateral pressure evaluation method and the lateral pressure evaluation device of the retaining wall according to the present invention are useful for the design of the retaining wall, and in particular, the excavation side more realistic for each next excavation stage of the retaining work in the alluvial ground. It is suitable for easily obtaining the depth distribution of lateral pressure.

1 Excavated soil mass 2 Root cutting bottom 3 Mountain retaining wall L Depth B Excavation width h Excavation depth

Claims (6)

It is a method to evaluate the excavation side pressure acting on the retaining wall when excavating the ground with a predetermined excavation width, depth, and depth.
Evaluation of the lateral pressure of the retaining wall, which is characterized by applying the normal stress at a position separated from the retaining wall by a predetermined distance from the retaining wall to the calculation formula by the Rankin-Rezal method to obtain the excavation side pressure at each next excavation stage. Method. The normal stress is the normal stress at a predetermined depth from the bottom of the root cutting when the excavated soil mass excavated and discharged is acted on the bottom of the root cutting as a deload, and is from the one-dimensional vertical soil cover pressure before excavation. The method for evaluating lateral pressure of a retaining wall according to claim 1, wherein the unloading stress due to the stress solution of Steinbrener is subtracted. The retaining wall according to claim 1 or 2, wherein the ground is an alluvial ground, and the normal stress is a vertical stress at a position separated from the retaining wall by 0.1 times the excavation width on the excavation side. Lateral pressure evaluation method. It is a device that evaluates the excavation side pressure acting on the retaining wall when excavating the ground with a predetermined excavation width, depth, and depth.
Evaluation of the lateral pressure of the retaining wall, which is characterized by applying the normal stress at a position separated from the retaining wall by a predetermined distance from the retaining wall to the calculation formula by the Rankin-Rezal method to obtain the excavation side pressure at each next excavation stage. apparatus. The normal stress is the normal stress at a predetermined depth from the bottom of the root cutting when the excavated soil mass excavated and discharged is acted on the bottom of the root cutting as a deload, and is from the one-dimensional vertical soil cover pressure before excavation. The lateral pressure evaluation device for a retaining wall according to claim 4, wherein the unloading stress due to the stress solution of Steinbrenner is subtracted. The retaining wall according to claim 4 or 5, wherein the ground is an alluvial ground, and the normal stress is a vertical stress at a position separated from the retaining wall by 0.1 times the excavation width on the excavation side. Side pressure evaluation device.

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