In foundation pit engineering, the force of the trenchless side on the enclosure structure must be a

Foundation pit works with an excavation depth of less than 5 meters are not regarded as deep foundation pit works. () Dear! Hello, happy to answer your <>

The general excavation depth is 5m and less than the shallow foundation pit (groove), and the digging depth of more than 5m is called the deep foundation pit (groove). Deep foundation pit refers to the excavation depth of more than 5 meters (including 5 meters) or more than three layers of basement (including three layers), or the depth is not more than 5 meters, but the geological conditions, surrounding environment and underground pipelines are particularly complex. According to the Ministry of Housing and Urban-Rural Development of the People's Republic of China on May 13, 2009 issued the "Measures for the Safety Management of Sub-project Safety Management Measures for the Greater Danger of Burning Tongtong", the deep foundation pit project is:

A) excavation depth of more than 5m (including 5m) of the foundation pit (groove) of the earthwork wheel which excavates, supports, and dewatering projects. (2) Although the excavation depth does not exceed 5m, the geological conditions, the surrounding environment and the underground pipeline are complex, or the earthwork excavation, support and dewatering engineering of the foundation pit (groove) that affects the safety of adjacent buildings (structures) hope that I can help you <>

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Answer]: B The test point involved in this question regrets that this is a deep foundation pit excavation. Basin excavation is to excavate the soil in the middle part of the foundation pit first, leave the soil slope on the four sides around, and the soil slope is finally excavated.

Advantages: The surrounding soil slope can be used to support the retaining wall, which is conducive to reducing the pre-permeability grinding of the retaining wall. Cong Dou disadvantages:

A large number of earthworks cannot be directly transported, and they need to be loaded and transported after centralized lifting.

Answer]: A2021 Textbook P90 2020 Textbook P89

The excavation scheme of deep foundation pit engineering mainly includes slope excavation, central island (also known as pier) excavation, basin excavation and Naxi reverse method excavation. The former has no support structure, and the last three macros all have support knots.

Answer] :d p 102 The excavation scheme of deep foundation pit engineering mainly includes slope excavation, center island excavation, basin excavation and reverse method excavation. The former has no supporting structure, and the latter three have supporting structures. Swift Age.

Summary. The excavation depth of 2m is planned to be calculated at a depth of 6m, and the general experience is: the length of the exposed steel sheet pile after earthwork excavation is one-third of the length of all steel sheet piles; 2m exposed, 4m buried.

There is no reason for the audit to deny the piling length, and the construction unit and the supervision unit can confirm the actual piling depth.

Generally, the depth of steel sheet piles is determined according to the depth of the groove and the quality of the soil, for example, the depth of the groove is 6 meters, and the steel sheet pile should be at least 12 meters long.

For the following types of enclosures, in general, the deepest excavation depth is:

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Steel plate crack early pile belongs to the temporary support pile, the general source of stupid excavation depth shall not exceed meters, the depth of more than 5 meters belongs to the deep foundation pit engineering, the support party to accompany the case needs expert demonstration, steel sheet pile is not in line with the use of requirements.

The excavation depth of 2m is planned to be calculated at a depth of 6m, and the general experience is: the length of the exposed steel sheet pile after earthwork excavation is one-third of the length of all steel sheet piles; 2m exposed, 4m buried. There is no reason for the audit to deny the piling long eggplant ratio, and the construction unit and the supervision and management unit can confirm the actual piling depth.

Generally, the depth of steel sheet piles is determined according to the depth of the groove and the quality of the soil, for example, the depth of the groove is 6 meters, and the steel sheet pile should be at least 12 meters long.

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Answer]: A The test point involved in this question is the application of the well point precipitation method. When the excavation of the foundation pit is deep, the water inflow of the foundation pit is large, and there is an enclosure structure, the well point precipitation method should be selected.

That is, the true wide rough empty (light) well point, jet well point or tube well go deep into the aquifer, and use the square bench of continuous pumping to reduce the groundwater level below the bottom of the pit, and at the same time make the carefully bent soil produce consolidation to facilitate earthwork excavation.

Answer]: a, d, e

The test point involved in this question is the applicable conditions for the foundation pit of the enclosure structure. If the foundation pit is very deep, the geological conditions are poor, the groundwater level is high, the special Zhaodan is not in the bustling urban area, the ground buildings are dense, the traffic is busy, there is not enough vacant land to meet the construction needs, there is no condition to use the open cracking guess hail slope foundation pit, then the foundation pit with enclosure structure can be used.

In the foundation pit excavation project, the phenomenon of failure of the supporting structure is:

Factors leading to foundation pit failure: 1. The design safety is not enough, and the consideration is not thorough 2, the design concept is wrong 3, the designer is not familiar with the local soil properties 4, the survey data is not perfect, the reliability is poor 5, the geological situation is abrupt 6, the construction is not in accordance with the requirements of the design drawings 7, the construction quality of the retaining pile (wall) 8, the construction quality of the mixing pile (jet grouting pile) 9, the construction quality of the anchor rod (soil nail) 10, the construction quality of the support rod 11, the internal damage of the support rod (internal injury) 12, The enclosure structure does not reach the design strength excavation 13, the excavator and the vehicle destroy the enclosure structure 14, the excavator and the vehicle hovering support operation 15, and the construction load outside the foundation pit exceeds the design allowability, especially the dynamic load exceeds the standard; 16, the top of the foundation pit slope unloading is insufficient 17, the foundation pit is ultra-deep excavation, there is no design requirement for layered excavation 18, the foundation pit is exposed for a long time, the cushion and the floor are not followed up in time The bad climate has been shadowed for a long time 19, the impact of surrounding excavation and piling construction on the foundation pit 20, and the waterproof curtain fails.