CN107816034B - Method for ramming soil mass to consolidate soil site by rammer - Google Patents
Method for ramming soil mass to consolidate soil site by rammer Download PDFInfo
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- CN107816034B CN107816034B CN201711106672.0A CN201711106672A CN107816034B CN 107816034 B CN107816034 B CN 107816034B CN 201711106672 A CN201711106672 A CN 201711106672A CN 107816034 B CN107816034 B CN 107816034B
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D3/00—Improving or preserving soil or rock, e.g. preserving permafrost soil
- E02D3/02—Improving by compacting
- E02D3/046—Improving by compacting by tamping or vibrating, e.g. with auxiliary watering of the soil
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D1/00—Investigation of foundation soil in situ
- E02D1/08—Investigation of foundation soil in situ after finishing the foundation structure
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- Life Sciences & Earth Sciences (AREA)
- Structural Engineering (AREA)
- Civil Engineering (AREA)
- Soil Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Mining & Mineral Resources (AREA)
- Paleontology (AREA)
- General Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Agronomy & Crop Science (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
- Force Measurement Appropriate To Specific Purposes (AREA)
Abstract
The invention relates to a method for reinforcing soil sites by ramming soil with a rammer, wherein a soil pressure box, a signal trigger on the rammer, the soil pressure box and a dynamic signal collector are used for obtaining the time used in the working process of the rammer in the rammer, and the effective work and energy loss of the rammer in each ramming process can be calculated by measuring the compression height of the soil with a traditional method. The horizontal stress attenuation path and the vertical stress attenuation path can be obtained by measuring the stress under different ramming modes, particularly the distribution of horizontal stress fields and vertical stress fields of different rammers under the action of ramming vibration waves is measured, and the stress distribution diagram during ramming can be obtained by superposing the measured data of horizontal stress attenuation of different layers on the forward direction. The traditional ramming process is scientized by evaluating the effective work for reinforcing the earthen site, scientific parameters are provided for the traditional ramming process, and positive contribution is made to the protection of the earthen site.
Description
Technical Field
The invention relates to the field of earthen site protection test research and protection reinforcement, in particular to a scientific interpretation and research method for reinforcing an earthen site by ramming a soil body by using a traditional rammer.
Background
The ancient soil remains in Xinjiang, gansu, ningxia and Shanxi areas of northwest China, the great wall in the northern area of the sinuous, the ancient city of the edge-closure on Gobi in northwest, the front flint, the Jiang river, gao Chang, lou lan and Niya remains in Xinjiang, thousands of years up and down, and the Ver-and-wan is spread over the China area. The histories of the earthen sites are long, some are listed as world cultural heritage, and have high cultural relic archaeological value. The primary task is to protect the authenticity and integrity of the site, namely the authenticity of relevant information such as histories, cultures, society and the like reflected by the materials, the process, the design and the environment of the site itself, and the integrity of the site body, the carrier and the surrounding environment. The protection of the site body not only solves the problem of the body and the salient surrounding environment through the protection measures, but also deeply researches the site building materials, processes, structures and disease reasons, thereby truly and completely inheriting the original site process technique and the use method of the materials. For a long time, the traditional ramming process is often carried out by experience in a first-generation way, and the specific advantages and disadvantages of the ramming density, the weight of the rammer, the impact stress and the ramming soil mass are rarely explored. In a great number of ancient soil sites on-site surveys, it is found that diseases generated by the soil sites are related to the traditional processes of tamping density, rammer impact and the like besides the influence of the climate environment on soil. The impact force of the rammer is large, the pit of the rammer is deep, and the soil layer is solid; otherwise, the impact force of the rammer is small, the hammer pit is shallow, and the soil layer is weak. And the diseases generated by the earthen site are often corroded from the deficient place of the soil layer, so that the rammed body is cracked or a crack is formed at the top of the contact surface of the rammed body and the original site of the support. Therefore, scientific interpretation of the traditional ramming process is the basis for further cognition and improvement of the traditional ramming process. The invention adopts the traditional process technique, establishes a mechanical model of the traditional ramming process through a large number of experiments by means of a pressure box detection method, fits different rammer acting stress characteristics and stress influence ranges through field experiments, and provides technical parameters for the earth site ramming support reinforcing technology so as to ensure the quality requirements of the ramming process.
Aiming at the defects that the ramming quality is often comprehensively judged by experience, manual observation, touch and other modes in the traditional ramming process, and is greatly influenced by human subjective. The invention aims to provide a method for ramming soil mass to consolidate soil sites by using a traditional rammer process. The impact range of the compaction density of the single-layer soil pavement and the multi-layer soil pavement in the compaction process is comprehensively analyzed through the monitoring of the pressure box, so that scientific guidance is provided for the traditional compaction process.
The invention aims at realizing the following technical scheme:
a method for ramming soil mass to strengthen soil site by ramming hammer includes the following steps:
(1) Pre-test inspection
The soil pressure box is horizontally placed, the soil pressure box is preheated for half an hour after being powered on, the soil pressure box is cleared after the resistance in the circuit is stable, the numerical fluctuation of the soil pressure box is tested to be smaller than the measurement precision of the soil pressure box, and data acquisition can be carried out;
(2) Tamping and leveling
The foundation layer laid by the soil pressure boxes is required to be leveled by shoveling out the virtual soil area, and the foundation layer is tamped for at least 6-8 times by a stone pestle, so that the foundation layer is ensured to be sufficiently compact;
(3) Sand laying
Spreading sand at the position on the foundation layer of the marking pressure box, wherein the thickness is 2-4mm, and the sand spreading area is not less than 3 times of the surface area of the soil pressure box;
(4) Pressure box layout
Placing the soil pressure boxes horizontally above the paved sand layer, wherein the distance between the soil pressure boxes is not more than 10cm, ensuring that the pressure boxes are centered and smooth and upward, and leading out pressure box leads from the foundation layer;
(5) Soil paving
Covering the soil pressure box and the lead wire with soil, wherein the thickness of the soil is 12-20cm;
(6) Data acquisition
The pressure cell lead wire is connected with a data acquisition device for acquiring the data of the soil pressure cell in real time, the sampling frequency is 1000Hz,
(7) Trigger sensor installation and ramming
A trigger is arranged on the plane of the rammer, the trigger is a vibration sensor or a capacitance sensor, the trigger can excite and collect signals at the moment that the rammer is contacted with soil, and for the rammer layer with the same soil paving thickness, the rammer layer is generally rammed for eight times, and the impact force of each rammer is collected;
the tamping mode is to tamp according to the mode of tamping the sea nest for the first time and tamping the silver ingot for the second time, and tamping is alternately performed on the sea nest and the silver ingot for the third time and the eighth time;
(8) Multi-layer laminated horizontal stress range test
The impact force of the rammer is relatively larger in the impact range, the stress values of different layers are different, the integral attenuation in the horizontal direction is faster than that in the vertical direction, the horizontal influence range of the integral impact acting force from the first layer to the sixth layer is not more than 12cm, and the linearity tends to be reduced.
(9) Vertical ram force attenuation law
Each layer is rammed for eight times, six layers of soil are paved, the thickness of each layer of soil is 20cm,16cm,12cm and 12cm respectively, and the impact stress detected by the soil pressure box is gradually reduced along with the increase of the height of the soil site wall;
the curve change can be divided into three stages, wherein the wall height is 10cm-20cm, the slope of the curve is the largest and approximates a straight line, the slope of the curve is 20cm-40cm, the slope of the curve is the second stage, the slope of the curve is smaller, the slope of the curve is 40cm-70cm, the slope of the curve is the third stage, and the slope of the curve is the smallest;
(10) Making stress contour plots
Aligning and forward superposing data measured by corresponding horizontal force attenuation and vertical force attenuation of different layers from a first layer to an N layer, dividing grids of the data points according to a coordinate system, and smoothly connecting points with the same numerical value to obtain a stress equivalent curve graph;
the invention has the advantages that:
(1) Through reasonable layout of the soil pressure box, the distribution condition of the stress field in the soil body can be detected when the rammer is used for ramming the soil body under the impact vibration effect of the rammer.
(2) Different soil paving thicknesses can be detected, and in the process of ramming the soil body by the rammer, the impact stress level and the vertical change rule in the process of gradually compacting the soil body along with the increase of the ramming times.
(3) The invention can test the stress attenuation degree in the horizontal direction and the vertical direction when the rammer is rammed, namely the vertical influence depth of the ramming vibration is far greater than that in the horizontal direction.
(4) The invention can detect the change of the effective work of the rammer during each ramming, and generally the effective work of the rammer tends to 0 along with the gradual compaction of the soil body, so that the compaction degree of the rammed soil body can be effectively evaluated.
(5) The invention detects the impact force of the rammer in the traditional ramming technology, is beneficial to knowing the stress change and the soil extrusion deformation process in the wall ramming process, thereby providing a scientific ramming method for reinforcing the earthen site, improving the quality and efficiency of the earthen site protection engineering, and having very important significance for scientific research of the ramming traditional technology and the earthen site protection maintenance quality.
(6) The method is simple and practical, convenient to operate and low in cost, and has wide application scenes in the aspect of the research of the soil building site ramming technology mechanics in arid and semiarid regions.
Drawings
FIG. 1 is a schematic plan layout of a pressure cell of the present invention;
FIG. 2 is a schematic representation of the ram of the present invention;
FIG. 3 is a schematic representation of the ramming mode of the present invention; the left part of the figure is the head ramming sea split position, and the right part of the figure is the two ramming silver blossom split position;
FIG. 4 is a 20cm recorder image of eight rammed earth passes of the signal triggering and acquisition system of the present invention;
FIG. 5 is a graph of the horizontal stress attenuation of six layers of paved soil according to the present invention;
FIG. 6 is a schematic diagram showing the variation rule of impact stress of the pressure box according to the invention along with the height of the wall;
FIG. 7 is a graph of stress contours at different depths according to the present invention.
Detailed Description
The invention selects rammer with mass of 5.5kg, the measuring range of the pressure box is 0.02-2MPa, the diameter of the pressure box is less than 30mm, the number of the pressure boxes is 10, the dynamic sampling frequency is 1000Hz, and the area of the test area is 4m 2 （2m×2m）。
The technical scheme of the invention is further described below with reference to the accompanying drawings:
a method for ramming soil mass to strengthen soil site by ramming hammer includes the following steps:
(1) Pre-test inspection
The soil pressure box 1 is horizontally placed, is preheated for half an hour after being powered on, is cleared after the resistance in the circuit is stable, and can acquire data when the numerical fluctuation of the resistance is tested to be smaller than the measurement precision;
(2) Tamping and leveling
The foundation layer laid by the soil pressure box 1 is required to be leveled by shoveling out the region with the deficient soil, and the foundation layer is rammed for 6-8 times at least by a stone pestle (15 Kg of flat bottom rammer weight and 18cm in diameter), so that the foundation layer is ensured to be sufficiently compact;
(3) Sand laying
Marking the point where the soil pressure box 1 is placed, and paving sand at the position where the foundation layer of the soil pressure box is placed, wherein the thickness is 2-4mm, and the sand paving area is not less than 3 times of the surface area of the soil pressure box 1, so as to eliminate the local difference of stress caused by medium non-uniformity;
(4) Pressure box layout
The soil pressure boxes 1 are horizontally arranged on the paved sand layer, the general interval is not less than 10cm, the centering and smooth surface facing of the soil pressure boxes 1 are ensured, and the two sides of the soil pressure boxes 1 are lightly pressed by hands, so that the soil pressure boxes cannot move; the lead wires 5 of the soil pressure box are distributed in a serpentine shape, are led out from the base layer, and record the serial numbers of the soil pressure box and the lead codes of the soil pressure box;
(5) Soil paving
A small amount of test soil is paved on the pressure box lead 5, the pressure box lead 5 is fixed, then soil is slowly compacted from the right upper side of the soil pressure box 1, the soil pressure box 1 is covered, after all the soil pressure boxes 1 are covered, soil is paved on the soil pressure box 1 according to the test requirement, the paving thickness is 12-20cm, and the soil pressure box 1 is ensured not to deviate;
(6) Data acquisition
The pressure box lead 5 is connected with the data collector 4, the data of the soil pressure box 1 are collected in real time, the sampling frequency is 1000Hz, and the data are not stopped in the middle of the data collection to ensure the accuracy of the data until the test is completed;
(7) Trigger sensor installation and ramming method
A trigger 3 is arranged on the plane of the rammer 2, and the trigger 3 is a vibration sensor or a capacitance sensor and can excite and collect signals at the moment that the rammer 2 is contacted with the soil body 6; for the ramming layer with the same soil paving thickness, the ramming is generally performed for eight times, and the impact force of each rammer is collected. As can be seen from fig. 5, the first pass, the soil pavement is approaching the foundation layer, the soil is weak, the data collector 4 shows small impact stress of the rammer, the seventh pass data collector shows maximum impact stress of the rammer with increasing number of ramming passes, the eighth pass data collector shows that the impact stress of the rammer remains almost unchanged or begins to decay, at which time the soil mass 6 has reached the ramming density.
The ramming mode is to perform ramming according to the mode of punching sea pits in the first time and punching silver ingots in the second time, the ramming mode of punching sea pits and punching silver ingots in the third time and the eighth time is to perform ramming alternately, the ramming direction is parallel to the arrangement direction of the soil pressure boxes, and pressure data and acting time of the soil pressure boxes are collected;
(8) Multi-layer compressive stress influence range test
The impact force impact range of the rammer 2 is relatively large, the stress values of different layers are different, the overall attenuation in the horizontal direction is faster than that in the vertical direction, and the multi-layer laminated horizontal stress range test is shown in fig. 5. Typically, the soil is paved 6 times. As can be seen from fig. 6: the impact force of the rammer is fast in attenuation, the impact effect of the ramming is hardly monitored in the sixth layer, and the impact force of the ramming in the sixth layer is less than 1/15 of the impact force of the first layer of soil paving thickness ramming.
(9) Vertical ram force attenuation law
Six layers of soil are paved on the wall body of the earthen site, and each layer is tamped for eight times. The thickness of each layer of soil is 20cm,16cm,12cm and 12cm respectively, and the impact stress detected by the soil pressure box 1 is also smaller and smaller. FIG. 6 shows that the fluctuation index of the first layer soil pressure box is 0.38KPa, and the fluctuation index of the soil pressure box approaches the minimum measuring range of 0.2KPa when the height of the soil site wall body increases to the sixth layer. The curve change can be divided into three stages, wherein the wall height is 10cm-20cm, the slope of the curve is maximum and approximates a straight line, the slope of the curve is 20cm-40cm, the slope of the curve is reduced, the slope of the curve is 40cm-70cm, the slope of the curve is minimum, and the slope of the curve is the third stage. According to the statistics value of impact stress of soil compaction density, it is found that y=A+Be exists between impact stress Y and ramming layer height X x /C And the fit is relatively good (the statistical analysis of the measured values of the impact stress when each layer is rammed for 7 times is shown in fig. 6, and the fit equation is shown in the table below).
Rammer lamination compaction impact force fitting equation
(10) Making stress contour plots
And linearly arranging soil pressure boxes 1 at equal intervals in the rammed soil, collecting rammed soil pressure of different soil paving thicknesses, aligning and forward superposing data measured by horizontal stress attenuation of different layers from a first layer to an N layer, dividing the stress points into grids, and smoothly connecting points with the same value to obtain a stress contour graph.
Claims (1)
1. A method for ramming soil mass to strengthen soil site by ramming hammer includes the following steps:
a. pre-test inspection
The soil pressure box (1) is horizontally placed, is preheated for half an hour after being powered on, is cleared after the resistance in the circuit is stable, and is tested to have the value fluctuation smaller than the measurement precision, and data acquisition is carried out;
b. regional tamping leveling
Before laying a foundation layer in the soil pressure box (1), leveling the area, and tamping the foundation layer for 6-8 times by using a flat stone pestle;
c. sand laying
The sand is paved at the position on the foundation layer of the soil pressure box (1) with the thickness of 2-4mm, and the sand paving area is 3 times of the upper surface area of the soil pressure box;
d. pressure box layout
The soil pressure box (1) is horizontally arranged on the paved sand, the smooth surface faces upwards, and the pressure box leads (5) are led out from the foundation layer;
e. soil paving
Covering the soil pressure box (1) and the pressure box lead (5) with soil, wherein the soil paving thickness is 12-20cm;
f. data acquisition
The pressure box lead (5) is connected with the data acquisition device (4) to acquire the pressure born by the soil pressure box (1) in real time, the sampling frequency is 1000Hz,
g. trigger sensor installation and ramming
A trigger (3) is arranged on the plane of the rammer (2), and the trigger (3) is a vibration sensor or a capacitance sensor and can excite an acquisition signal at the moment that the rammer (2) is contacted with a soil body (6); for the rammed layer with the same soil paving thickness, paving 20cm of soil, and ramming for eight times; the ramming mode is to perform ramming according to the mode of the first sea nest ramming, the second silver ingot ramming, the third-eighth sea nest ramming mode and the silver ingot ramming mode are alternately performed,
h. multi-layer laminated horizontal stress range test
The impact force impact range of the rammer (2) is large, the stress values of different layers are different, and the integral attenuation in the horizontal direction is faster than that in the vertical direction;
i. vertical ram force attenuation law
Six layers of soil are paved for eight times, the thickness of each layer of soil is 20cm,16cm,12cm and 12cm respectively, and the impact stress detected by the soil pressure box (1) is smaller and smaller along with the increase of the height of the wall of the soil site;
j. making stress contour plots
And (3) aligning and forward superposing data measured by horizontal stress attenuation and vertical stress attenuation of different layers from the first layer to the N layer, dividing the data points into grids according to a coordinate system, and smoothly connecting points with the same numerical value to obtain a stress equivalent curve graph.
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000110155A (en) * | 1998-10-01 | 2000-04-18 | Nishimatsu Constr Co Ltd | Stabilized soil specimen making rammer |
| CN103196599A (en) * | 2013-03-19 | 2013-07-10 | 西北大学 | System and method for monitoring soil body inner stress variation of loess field under soaking condition |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000110155A (en) * | 1998-10-01 | 2000-04-18 | Nishimatsu Constr Co Ltd | Stabilized soil specimen making rammer |
| CN103196599A (en) * | 2013-03-19 | 2013-07-10 | 西北大学 | System and method for monitoring soil body inner stress variation of loess field under soaking condition |
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