Supporting construction technology for deep foundation pit nearby road on complicated geological conditions

A technology of complex geological conditions and deep foundation pit support, applied in infrastructure engineering, sheet pile walls, excavation, etc., can solve problems such as difficult support for deep foundation pits, high construction costs, and potential safety hazards, and eliminates the need for Potential safety hazards, reduced construction costs, and the effect of reducing the amount of backfill

Pending Publication Date: 2020-01-14

中铁八局集团第四工程有限公司 +1

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Problems solved by technology

[0004] The purpose of the present invention is to: aim at the above existing problems, to provide a deep foundation pit support construction technology adjacent to the road under complex geological conditions, the present invention adopts the method of inclined col...

Method used

Further, considering that the rubble that rock layer 4 side slopes tumbles can form impact on the second column pile 901 of the second inclined column support 9, particularly the second column pile 901 is connected with the bottom of the foundation pit, The resulting stress concentration is relatively large, as shown in Figure 1, the buffer soil layer 10 is formed by filling soil between the rock retaining plate 902 and the slope of the rock layer 4, so as to solve the problem of stress concentration at the joint caused by the impact of gravel on the column pile .

Further, considering the convenient problem of early stage rammed earth backfill and later stage clearing, the backfill height of described buffer soil layer 10 is between the 2/5-3/5 of described second column pile 901 height, and it can Choose 2/5, 5/10 or 3/5, and the specific value is selected according to the actual situation. This setting method can reduce the amount of backfill rammed earth as much as possible, and at the same time ensure the basic role that the buffer soil layer 10 can play.

In above-mentioned construction technology, it is applicable to the deep foundation pit support construction that there are two kinds of stratum structures of soft and hard when excavating deep foundation pit, that is to say, rock layer in the above-mentioned ...

Abstract

The invention discloses a supporting construction technology for a deep foundation pit nearby a road on the complicated geological conditions. The technology comprises the following steps of first, carrying out foundation pit excavation to the lithosphere, and carrying out slope setting construction to form a first foundation pit; second, driving first column piles on the edge of the pit bottom ofthe first foundation pit to form first batter post supporting; third, carrying out lithosphere excavation at the pit bottom of the first foundation pit to form a second foundation pit, carrying out slope setting construction, and then carrying out anchor rod supporting; and fourth, driving second column piles on the edge of the pit bottom of the second foundation pit to form second batter post supporting. According to the supporting construction technology for the deep foundation pit nearby the road on the complicated geological conditions, supporting on the deep foundation pit is implementedin the manner of arranging anchor rod supporting between batter post supporting, the problems that supporting for a deep foundation pit nearby the road on complicated geological conditions is difficult to carry out, high in construction cost, prone to having potential safety hazard, and the like are solved, supporting construction of the deep foundation pit nearby the road on the complicated geological conditions can be implemented, and the successful practice experience is provided for the field of supporting construction.

Application Domain

ExcavationsBulkheads/piles

Technology Topic

LithosphereDeep excavation +2

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Examples

Experimental program(1)

Example Embodiment

[0020] Example

[0021] Take the CLZF-2 standard project of Chengdu to Chuanzhusi section of Chenglan Railway undertaken by the applicant as an example. The project includes 5 station buildings including Maoxian Station, Zhenjiangguan Station, Songpan Station, Chuanzhusi Station, and Huangshengguan Station. Among them, during the construction of the Huangshengguan and Chuanzhusi station buildings, the temporary site was relatively narrow, the excavation line of the foundation pit was about 50cm away from the temporary road on the site, the depth of the foundation pit was more than 5m, the geological conditions were complicated, and the upper part of the ground was loose and humid. The lower part is a very high soil layer, and the lower part is a hard and compact rock layer. The traditional supporting structure cannot be applied. In order to solve this problem, the present invention figure 1 As shown, the deep foundation pit support construction technology adopted by the present invention includes the following steps:

[0022] Step 1. Excavate the foundation pit beside the roadbed 1 until the bottom of the foundation pit reaches the rock layer 5. That is, first dig 2-3m until the relatively soft soil layer is digged, and at the same time, the formed foundation pit is sloped , The first foundation pit 2 is formed, and the grading construction is selected according to the original design requirements according to the slope slope and slope coefficient in the grading construction, for example, 1:0.5 can be used in this embodiment;

[0023] Step 2. Set up the first pillar pile 501 along the edge of the first foundation pit, and set the retaining plate 502 on the inner side of the first pillar pile 501 and use the first diagonal brace 503 to support the top. The inner side of the retaining plate is filled with soil and tamped to form the first Inclined pillar supports 5, and the rammed earth layer forms a backfill layer 6;

[0024] Step 3. Excavate the rock layer 5 at the bottom of the first foundation pit 2 to form the second foundation pit 3. The starting point of excavation is 0.5-2m from the first diagonal brace (in this embodiment, the starting point of excavation is 1.5m as the most Appropriate), the inclined support platform 7 is formed. The excavation depth of the second foundation pit 3 reaches the designed depth of 3m. When the second foundation pit 3 is excavated, the second foundation pit 3 needs to be graded. The slope is 1:0.25;

[0025] Step 4. According to the existing construction standards for bolt support, anchor the rock wall of the second foundation pit 8 is drilled to the design depth, put a tie rod in the hole, and pour cement mortar and The rock is combined into a reinforced anchor rod with strong tensile strength. One end of the reinforced anchor rod is fixed on the rock wall and the other end is anchored in the rock layer. The stability of the rock slope is protected by the anchor rod support. As a preferred example, it can also adopt other bolt support structures, such as wire rope mortar bolt support or pipe joint type bolt support);

[0026] Step 5: A second pillar pile 901 is built along the edge of the bottom of the second foundation pit 3, a stone retaining plate 902 is supported on the inner side of the second pillar pile 901, and a second diagonal brace 903 is used to support the top to form a second inclined pillar support 9.

[0027] In the above construction process, the first inclined column support 5 used in the first foundation pit 2 is an existing common inclined column support structure, and its construction requirements and construction operations can be implemented in accordance with the existing standards, that is, the retaining plate 902 is fixed at The inner side of the first pillar 501, the outer side of the first pillar 501 is supported by the first diagonal brace 503, the bottom of the first diagonal brace 503 is on the wooden brace pile 504, and the inner side of the retaining plate 502 is backfilled with soil, which will not be described in detail here . Correspondingly, the second inclined column support adopted in the second foundation pit 3 is also the existing common inclined column support structure, which can be implemented in accordance with the existing construction standards. In order to better enable the support of the second inclined column to play the role of supporting stones, the retaining plate 502 is replaced with a concrete or steel stone retaining plate 902 with greater material strength, which does not need to be backfilled inside the stone retaining plate 902 to form a backfill layer 6.

[0028] Further, considering that the rubble falling from the side slope of the rock layer 4 will impact the second pillar 901 of the second inclined pillar support 9, especially the connection between the second pillar 901 and the bottom of the foundation pit, The stress concentration is greater, such as figure 1 As shown, the soil is filled and tamped between the stone retaining plate 902 and the side slope of the rock layer 4 to form a buffer soil layer 10 to solve the problem of stress concentration at the connection caused by the impact of gravel on the pile.

[0029] Further, taking into account the problems of rammed earth backfilling in the early stage and the convenience of later site clearance, the backfilling height of the buffer soil layer 10 is between 2/5-3/5 of the height of the second pillar 901, which can be selected as 2/ 5, 5/10 or 3/5, the specific value is selected according to the actual situation, this setting method can reduce the amount of backfilled rammed earth as much as possible, while ensuring the basic function of the buffer soil layer 10.

[0030] In the present invention, because it belongs to the deep foundation pit support construction, the rock layer 4 part has the problem of rock seepage. In order to facilitate the removal of this part of water, the side slope of the rock layer 4 and the pit of the second foundation pit 3 A drainage ditch 11 is excavated at the bottom joint, and the drainage ditch 11 forms a ring shape along the joint. The top of the drainage ditch 11 is covered with a cover plate (not shown in the figure) with a through hole or a through groove. The buffer soil layer 10 Located on the cover. The seepage water of the slope of the rock layer 4 penetrates into the drainage ditch 11 through the buffer soil layer 10, and then is drained to the drainage place through the drainage ditch 11, which solves the adverse effect of the rock seepage on the foundation pit.

[0031] In the above construction technology, it is suitable for deep foundation pit support construction where there are two types of stratum structures, soft and hard, when excavating deep foundation pits, that is, when the rock layer in the above embodiment is replaced with a harder soil layer, It is also applicable. The support of deep foundation pits is realized by adopting inclined column support + anchor rod support + inclined column support, which solves the difficulty of deep foundation pit support and construction near roads under complex geological conditions. Problems such as high cost and potential safety hazards have realized the support construction of deep foundation pits adjacent to roads under complex geological conditions, and provided successful practical experience in the field of support construction.

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Classification and recommendation of technical efficacy words

Reduce construction costs
Reduce the amount of backfill

Supporting construction technology for deep foundation pit nearby road on complicated geological conditions

AI-Extracted Technical Summary

Problems solved by technology

Method used

Abstract

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Examples

Example Embodiment

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Description & Claims & Application Information

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