CN113026666A - Outer-isolation inner-discharge type weak expansive soil surface layer slope treatment device and construction method thereof - Google Patents

Abstract

The invention discloses an external-isolation internal-discharge type weak expansive soil surface layer slope treatment device, and relates to the field of engineering slope treatment of water conservancy, roads, bridges and the like. The soil comprises a weak expansion soil layer, an internal drainage layer and an external replacement layer; the inner drainage layer comprises a drainage blind ditch and a drainage pipe; the outer replacement layer comprises a weak expansion soil terrace layer and a cement modified soil layer. The external displacement layer adopts non-expansive clay with certain thickness to displace and fill the expansive soil on the surface layer of the slope, so that the water content of the lower expansive soil body is not changed violently, and the external displacement layer is simple in construction, easy to operate and good in effect. The invention also relates to a construction method of the external-isolation internal-drainage weak expansive soil surface layer slope treatment device.

Description

Outer-isolation inner-discharge type weak expansive soil surface layer slope treatment device and construction method thereof

Technical Field

The invention relates to the field of slope treatment of projects such as water conservancy projects, highways, bridges and the like, in particular to an external-isolation internal-discharge type weak expansive soil surface layer slope treatment device. The invention also relates to a construction method of the external-isolation internal-drainage weak expansive soil surface layer slope treatment device.

Background

Dehydration cracking and water swelling are the most important characteristics of expansive soil and are also the important causes of landslide on the surface layer (1-3m) of the expansive soil slope, and the characteristics are mainly controlled by the water state in the soil body. When the moisture in the expansive soil body changes alternately, the expansive soil body is subjected to dry shrinkage cracking and wet expansion deformation repeatedly, so that the expansive soil body is loosened, and finally the expansive soil slope is deformed and damaged.

The existing domestic engineering practice shows that atmospheric precipitation and groundwater activity are important reasons for water alternation in the soil body of the expansive soil, after the expansive side slope is excavated and exposed to the atmospheric environment, the surface soil body is rapidly dehydrated, contracted, cracked and deformed to form reticular expansion and contraction cracks, the cracks exist in the shallow surface part of the soil layer in a drying and shrinkage cracking mode, and once atmospheric rainfall or groundwater infiltrates, the cracks can be rapidly closed under the action of expansion and deformation. Under the repeated dry-wet alternating action of climate after excavation, favorable soil deformation and damage conditions are formed when the reticular expansion-shrinkage cracks are cut by bedding surfaces and underground interfaces, and the expansion-shrinkage activity of the interfaces causes the occurrence of soil deformation and collapse damage.

Therefore, in order to prevent the surface layer of the expansive soil channel side slope from being damaged, the moisture state in the soil body must be effectively controlled to keep the stability of the soil body, and the most important measure is to prevent atmospheric precipitation and underground water from permeating into the expansive soil side slope. The conventional soil slope support is generally treated by adopting lattice concrete and turf revetment, but the measure cannot ensure the seepage prevention of atmospheric precipitation and the quick discharge of groundwater in the slope.

Therefore, it is necessary to develop an external-isolation internal-drainage type weak expansive soil surface layer slope treatment device.

Disclosure of Invention

The invention aims to overcome the defects of the background technology and provides an external-isolation internal-discharge type weak expansive soil surface layer slope treatment device.

The second purpose of the invention is to provide a construction method of the external-isolation internal-discharge weak expansive soil surface layer slope treatment device.

In order to achieve the first object, the technical scheme of the invention is as follows: outer separate interior row type weak expansion soil top layer slope improvement device, including weak expansion soil layer, its characterized in that: the soil conditioner also comprises an inner drainage layer positioned above the weak expansion soil layer and an outer replacement layer positioned above the inner drainage layer;

the inner drainage layer comprises a drainage blind ditch positioned above the weak expansion soil layer and a drainage pipe connected with the tail end of the drainage blind ditch;

the outer replacement layer comprises a weak expansion soil step layer positioned above the drainage blind ditch and a cement modified soil layer positioned above the weak expansion soil step layer.

In the technical scheme, the section of the drainage blind ditch is trapezoidal, and the side face and the bottom of the drainage blind ditch are paved with composite geomembranes; the drainage blind ditch comprises a plurality of dry blind ditches and a plurality of branch blind ditches.

In the technical scheme, sand gravel is back filled in the drainage blind ditch.

In the technical scheme, the width of the bottom of the drainage blind ditch is 0.5m, the width of the top of the drainage blind ditch is 0.8m, and the depth of the drainage blind ditch is 0.5 m; the distance between the dry blind ditches is 8 meters, and the distance between the branch blind ditches is 4 meters.

In the technical scheme, the cement modified soil is obtained by mixing weak expansive soil and cement, the cement modified soil is paved and rolled in layers to obtain a cement modified soil layer with the thickness of 300mm, and the step layer of the weak expansive soil is a step with the height of 25cm and the width of 1 m.

In order to achieve the second object, the invention has the technical scheme that: the construction method of the outer-isolation inner-discharge weak expansive soil surface layer slope treatment device is characterized by comprising the following steps of:

step 1: dredging drainage on the surface of the top of the channel slope and the adjacent terrain, preventing the surface water from washing the cleaned deformed body to build a base surface, and preventing water accumulation within 30 meters away from the opening line;

step 2: cleaning the deformation body to reach an original soil layer below the sliding surface, wherein soil body excavation is mechanical excavation, and an artificial cleaning surface with the thickness of 8cm is reserved for the expansive soil;

and step 3: arranging a drainage blind ditch between the changed filling soil and the cleaned slope surface, wherein the drainage blind ditch is made of gravel materials and broken stones, and is of a trapezoidal section, the bottom width of the drainage blind ditch is 0.5m, the top width of the drainage blind ditch is 0.8m, and the depth of the drainage blind ditch is 0.5 m;

400g/m of drainage blind ditch side and bottom paving²The two cloth and one film composite geomembranes have the thickness of 0.2 mm; a drain pipe is arranged at the tail end of the drain blind ditch along the longitudinal direction; the drain pipe is a phi 75PE63 pipe, and leads out the slope protection surface to form a complete internal drainage channel; the inlet of the drain pipe is plugged by geotextile;

and 4, step 4: crushing weak and medium expansive soil excavated in a channel to meet the design requirement, wherein the particle size of the soil material is not more than 10cm, the content of the particle size of 10cm-5cm is not more than 5%, the content of the particle size of 5cm-5mm is not more than 50%, and constructing by adopting a hydraulic soil crusher; mixing the crushed and screened expansive soil with 4% of cement by using a stable soil mixer and adding water for mixing, wherein the water content of the cement modified soil is 1.0% higher than the optimal water content during paving so as to compensate the water loss in the paving and rolling processes;

and 5: after the cement is qualified, the mixed cement is timely filled in a ditch in layers, and the filling thickness is 30 cm. In order to better combine the treatment layer with the side slope, the side slope surface is arranged and excavated into a small step shape by combining material spreading and flat warehouse construction, wherein the step height is 25cm, and the step width is 1 m; and (5) tamping by adopting a vibratory tamper, wherein the degree of compaction is not less than 94%, and the construction is finished.

Compared with the prior art, the invention has the following advantages:

1) the external displacement layer adopts non-expansive clay with certain thickness to displace and fill the expansive soil on the surface layer of the slope, so that the water content of the lower expansive soil body is not changed violently, and the external displacement layer is simple in construction, easy to operate and good in effect.

2) After the expansive soil in the cement modified soil layer is modified by adding cement, the expansive soil protective material has the advantages of convenient material taking, good stability and high strength, can prevent the shallow surface layer of the expansive soil channel slope from being damaged, effectively reduces the lifting deformation of the channel base, and plays a good role in protecting the internal expansive soil.

3) When the water content of the external replacement layer is changed, the change of the expansion and contraction property, the structural stability and the shear strength of the soil body is obviously higher than that of the protected soil body, so that the purpose of effectively protecting the protected body is achieved; the cement modified soil layer isolates expansive soil to directly act with the external environment, so that the expansive potential is absorbed, the shear strength of the soil body on the surface layer of the canal slope is improved, and the stability of the canal slope is further improved.

4) The external displacement layer of the invention can block the passage of atmospheric precipitation entering the expansive soil canal slope, and simultaneously reduce the underground water level, reduce the uplift pressure under the backfill layer and ensure the stability of the backfill layer;

5) the internal drainage layer of the invention drains seepage flow generated by infiltration of rainfall and infiltration of accumulated water after the slope, accelerates dredging of water on the slope, reduces water content change of expansive soil caused by infiltration of rainfall, and prevents water and soil loss of the slope.

6) The internal drainage layer can drain moisture out of the slope through the drainage blind end in time, so that the fluctuation and expansion and contraction of the moisture in the soil are weakened, and the crack surface is prevented from further expanding and developing inwards.

Drawings

FIG. 1 is a schematic structural diagram of the present invention.

Figure 2 is a plan view of the internal drainage layer.

Fig. 3 is a sectional view of the drain blind ditch.

Detailed Description

The embodiments of the present invention will be described in detail with reference to the accompanying drawings, which are not intended to limit the present invention, but are merely exemplary. While the advantages of the invention will be apparent and readily appreciated by the description.

With reference to the accompanying drawings: outer separate interior row type weak expansive soil top layer slope improvement device, including weak expansive soil layer 1, its characterized in that: the soil-water separation device also comprises an inner drainage layer 2 positioned above the weak expansion soil layer 1 and an outer displacement layer 3 positioned above the inner drainage layer 2;

the inner drainage layer 2 comprises a drainage blind ditch 21 positioned above the weak expansion soil layer 1 and a drainage pipe 22 connected with the tail end of the drainage blind ditch 21;

the outer replacement layer 3 comprises a weak expansive soil step layer 31 positioned above the drainage blind ditch 21 and a cement modified soil layer 32 positioned above the weak expansive soil step layer 31.

The section of the drainage blind ditch 21 is trapezoidal, and the side surface and the bottom of the drainage blind ditch 21 are paved with composite geomembranes 213; the drain blind ditch 21 comprises a plurality of dry blind ditches 211 and a plurality of branch blind ditches 212.

Gravel 214 or broken stones are filled in the drainage blind ditch 21.

The width of the bottom of the drainage blind ditch 21 is 0.5m, the width of the top is 0.8m, and the depth is 0.5 m; the spacing between the dry blind ditches 211 is 8 meters, and the spacing between the branch blind ditches 212 is 4 m.

The cement modified soil is obtained by mixing weak expansive soil and cement, the cement modified soil is paved and rolled in layers to obtain a cement modified soil layer 32 with the thickness of 300mm, and the step layer 31 of the weak expansive soil is a step with the height of 25cm and the width of 1 m.

The construction method of the outer-isolation inner-discharge weak expansive soil surface layer slope treatment device is characterized by comprising the following steps of:

step 1, dredging and draining: dredging drainage on the surface of the top of the channel slope and the adjacent terrain, preventing the surface water from washing the cleaned deformed body to build a base surface, and preventing water accumulation within 30 meters away from the opening line;

step 2, soil excavation: cleaning the deformation body to reach an original soil layer below the sliding surface, wherein soil body excavation is mechanical excavation, and an artificial cleaning surface with the thickness of 8cm is reserved for the expansive soil; soil body excavation stress concentration force rapid construction is realized, and the exposure time of a foundation surface is shortened as much as possible

And 3, constructing an internal drainage layer: a drainage blind ditch 21 is arranged between the soil replacement and the slope surface cleaning, the drainage blind ditch 21 is made of gravel materials and broken stones, the drainage blind ditch 21 is a trapezoidal section, the bottom width is 0.5m, the top width is 0.8m, and the depth is 0.5 m;

400g/m is paved on the side surface and the bottom of the drainage blind ditch 21²The two cloth one film composite geomembranes 213 are arranged, and the thickness of the film is 0.2 mm; a drain pipe 22 is arranged at the tail end of the drain blind ditch 21 along the longitudinal direction; the drain pipe 22 is a phi 75PE63 pipe, and leads out of the slope protection surface to form a complete internal drainage channel; the inlet of the drain pipe 22 is plugged by geotextile;

step 4, preparing cement modified soil: crushing weak and medium expansive soil excavated in a channel to meet the design requirement, wherein the particle size of the soil material is not more than 10cm, the content of the particle size of 10cm-5cm is not more than 5%, the content of the particle size of 5cm-5mm is not more than 50%, and constructing by adopting a hydraulic soil crusher; mixing the crushed and screened expansive soil with 4% of cement by using a stable soil mixer and adding water for mixing, wherein the water content of the cement modified soil is 1.0% higher than the optimal water content during paving so as to compensate the water loss in the paving and rolling processes;

step 5, constructing an external replacement layer: after the cement is qualified, the mixed cement is timely filled in a ditch in layers, and the filling thickness is 30 cm. In order to better combine the treatment layer with the side slope, the side slope surface is arranged and excavated into a small step shape by combining material spreading and flat warehouse construction, wherein the step height is 25cm, and the step width is 1 m; adopting vibration ramming to tamp, wherein the compaction degree is not less than 94%, modifying the expansive soil, and keeping the duration from adding water for mixing to the end of rolling for not more than 4 hours, wherein spring soil, loose soil and peeling phenomena exist in the rolling process, and the expansive soil is turned over in time and rolled again; and finishing construction.

The technical problem solved by the invention is as follows: the existing method applied to the treatment of the side slope on the surface layer of the weak expansive soil cannot effectively prevent atmospheric rainfall from permeating into the side slope of the expansive soil, and cannot quickly discharge underground water out of the side slope to directly influence the local and overall stability of the side slope.

In practical use, the invention mainly comprises an external displacement layer and an internal drainage layer, wherein the external displacement layer is used for isolating weak expansive soil and atmospheric precipitation and preventing the weak expansive soil from disintegrating and softening due to infiltration of the atmospheric precipitation; the effect of inside drainage blanket is outside discharging the slope fast with the inside groundwater of weak swelling soil side slope, prevents that the groundwater motion from leading to the fact the reason to draw to split and lead to the fact the falling tile formula destruction of canal slope.

Other parts not described belong to the prior art.

Claims (6)

1. Separate interior row's formula weak expansive soil top layer slope management device outward, including weak expansive soil layer (1), its characterized in that: the soil conditioner also comprises an inner drainage layer (2) positioned above the weak expansion soil layer (1) and an outer replacement layer (3) positioned above the inner drainage layer (2);

the inner drainage layer (2) comprises a drainage blind ditch (21) positioned above the weak expansion soil layer (1) and a drainage pipe (22) connected with the tail end of the drainage blind ditch (21);

the outer replacement layer (3) comprises a weak expansion soil step layer (31) positioned above the drainage blind ditch (21) and a cement modified soil layer (32) positioned above the weak expansion soil step layer (31).

2. The external-isolation internal-drainage weak expansive soil surface slope treatment device according to claim 1, which is characterized in that: the section of the drainage blind ditch (21) is trapezoidal, and the side surface and the bottom of the drainage blind ditch (21) are paved with composite geomembranes (213); the drainage blind ditch (21) comprises a plurality of dry blind ditches (211) and a plurality of branch blind ditches (212).

3. The external-isolation internal-drainage weak expansive soil surface slope treatment device according to claim 2, which is characterized in that: sand gravel (214) is back filled in the drainage blind ditch (21).

4. The outer-isolation inner-discharge type weak expansive soil surface layer slope treatment device according to claim 3, which is characterized in that: the width of the bottom of the drainage blind ditch (21) is 0.5m, the width of the top of the drainage blind ditch is 0.8m, and the depth of the drainage blind ditch is 0.5 m; the distance between the dry blind ditches (211) is 8 meters, and the distance between the branch blind ditches (212) is 4 m.

5. The outer-isolation inner-discharge type weak expansive soil surface layer slope treatment device according to claim 4, which is characterized in that: the cement modified soil is obtained by mixing weak expansive soil and cement, the cement modified soil is paved and rolled in layers to obtain a cement modified soil layer (32) with the thickness of 300mm, and the step layer (31) of the weak expansive soil is a step with the height of 25cm and the width of 1 m.

6. The construction method of the external-isolation internal-discharge weak expansive soil surface slope treatment device according to any one of claims 1 to 5, which is characterized by comprising the following steps:

step 1: dredging drainage on the surface of the top of the channel slope and the adjacent terrain, preventing the surface water from washing the cleaned deformed body to build a base surface, and preventing water accumulation within 30 meters away from the opening line;

step 2: cleaning the deformation body to reach an original soil layer below the sliding surface, wherein soil body excavation is mechanical excavation, and an artificial cleaning surface with the thickness of 8cm is reserved for the expansive soil;

and step 3: a drainage blind ditch (21) is arranged between the soil replacement and the slope surface cleaning, the drainage blind ditch (21) is made of gravel materials and gravels, the drainage blind ditch (21) is a trapezoidal section, the bottom width is 0.5m, the top width is 0.8m, and the depth is 0.5 m;

400g/m is paved on the side surface and the bottom of the drainage blind ditch (21)²The two cloth one film composite geomembranes (213) have the thickness of 0.2 mm; a drain pipe (22) is arranged at the tail end of the drain blind ditch (21) along the longitudinal direction; the drain pipe (22) is a phi 75PE63 pipe, and leads out of the slope protection surface to form a complete internal drainage channel; the inlet of the drain pipe (22) is plugged by geotextile;

and 4, step 4: crushing weak and medium expansive soil excavated in a channel to meet the design requirement, wherein the particle size of the soil material is not more than 10cm, the content of the particle size of 10cm-5cm is not more than 5%, the content of the particle size of 5cm-5mm is not more than 50%, and constructing by adopting a hydraulic soil crusher; mixing the crushed and screened expansive soil with 4% of cement by using a stable soil mixer and adding water for mixing, wherein the water content of the cement modified soil is 1.0% higher than the optimal water content during paving so as to compensate the water loss in the paving and rolling processes;

and 5: after the cement is qualified, the mixed cement is timely filled in a ditch in layers, and the filling thickness is 30 cm. In order to better combine the treatment layer with the side slope, the side slope surface is arranged and excavated into a small step shape by combining material spreading and flat warehouse construction, wherein the step height is 25cm, and the step width is 1 m; and (5) tamping by adopting a vibratory tamper, wherein the degree of compaction is not less than 94%, and the construction is finished.

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