Geotechnical engineering investigation and design not only need to guide and analysis, but also need to enrich the engineering experience, the article on the design of geotechnical engineering geological survey must pay attention to several issues discussed in the process.
One, the problem that should be paid attention to in the geotechnical engineering reconnaissance stage
The analysis and evaluation of geological conditions should be carried out in the whole process of design and construction of geotechnical engineering: the geological conditions determine the selection of engineering method, which determines the strength of the engineering method, and determines the choice of construction method. But because of the complexity of geological conditions, geological prospecting work required to fully meet the design needs is not possible, especially in the current highway geological survey in order to save funds rush deadlines, investigation, do not follow the normal procedure and the neglect of geological investigation scene investigation management and neglect of various surveying data under the condition of more comprehensive analysis and so on so, the investigation of geotechnical engineering design not only need guidance and analysis of theory, but also have rich engineering experience, geotechnical engineering geological investigation process must pay attention to the following questions:
(1) the difference between the physical and mechanical properties of rock (Yan Kuai) and "rock" is generally the physical and mechanical properties of rock, and it is generally considered that the physical and mechanical properties of rock mass, which is considered to be a comprehensive parameter, which can be converted to some experience, but the best method is the field test.
(2) the difference between the physical and mechanical properties of rock mass and weak structure plane for slope stability analysis of rock and soil we are more concerned about the large weak structural plane or different strata contact surface, the physical and mechanical properties of rock mass is more comprehensive than low.
(3) distinguish between "undisturbed soil" physical and mechanical parameters and "design value" of the relationship between physical and mechanical parameters of rock and soil physical and mechanical parameters of the test, because it can reflect the real situation, but due to rainfall and groundwater activities will greatly deteriorate the physical parameters of rock and soil parameters, if not in the corresponding conditions, directly to the original value of the test as a design, it may make the project is extremely dangerous.
(4) it is a great importance to implement the geotechnical engineering measures for the investigation of the distribution of rock and soil in the region.
(5) pay attention to the overall survey, engineering effect of physical and mechanical properties of rocks and soils in the region such as bulk density, void ratio, foundation bearing capacity, ultimate mold resistance, Neimocha angle, cohesive force, elastic modulus, Poisson's ratio and so on, the specific content and method should be determined according to the geological conditions and specific engineering measures.
Two. The problems that should be paid attention to in the design stage of geotechnical engineering
Geotechnical engineering design to be "feasible" is relatively simple, but it is very difficult to be "reasonable", because it not only depends on the terrain and geological conditions, but also on the construction method. First of all, we must design a preliminary design scheme according to the geological conditions. According to the preliminary design scheme, design scheme is feasible. Finally, the detailed design scheme, construction method and construction requirements are presented. In geotechnical engineering design process should pay attention to the following points:
(1) attention to the selection of a variety of methods. First, the effectiveness of the method should be ensured, and then the method is economical. In the rock, the effect of anchor reinforcement is better than that of the retaining wall, and the combination of protective measures and cutting slope in the soil layer is better than that of the simple reinforcement measures, and the combination of prestressed anchor cable and anti slide pile is better than that of anti slide piles.
(2) attention to the understanding of the permanent safety of the project. The creep deformation of soil, the corrosion of anchor, the relaxation of prestressing force and the water softening of soil will weaken the permanent safety of the protective structure.
(3) when the need to strengthen the protection measures to pay attention to distinguish the authenticity of the strengthening measures. Under some conditions, strengthening the protective measures may not increase the protective safety, such as increasing the anchor diameter or increasing the anchor density without increasing the anchor length, increasing the length of the pre stress anchor, increasing the length of the pile and the diameter of the pile.
(4) attention to the assessment of environmental impact. Rock and soil excavation is generally caused by near surface subsidence deformation, construction blasting in the vicinity of a larger vibration and noise, as well as a large change in the groundwater level caused by the near ground water reduction, surface water body can not keep long.
(5) in the course of design, the construction quality inspection and design modification conditions must be put forward, which is due to the complicated and changeable geological conditions in the field, and to ensure the construction quality of geotechnical engineering.
Therefore, it is not only an economic problem, but also an economic problem, which should be analyzed from the aspects of engineering feasibility, engineering safety, environmental protection, construction quality control and so on. In the case of the construction cost, the landslide should be avoided, because the landslide is not