Papers Category:Science Papers
- Geology Papers
Post Time:2011-4-4 16:09:00
Abstract: The hydro-geological survey and research in engineering has a very important position, this paper describes engineering geological evaluation of the content of hydro-geological exploration, soil hydraulic properties, groundwater hazards caused by issues such as geotechnical engineering.
Keywords:: engineering investigation, hydrogeological, geotechnical, hazardous
An engineering geological investigation in the evaluation of the content of hydrogeological
In engineering exploration, evaluation of hydrogeological problems should primarily consider the following:
1.1 The evaluation should focus on rock and soil and groundwater on the role and impact of buildings, predict possible geotechnical hazards, proposed control measures.
1.2 Engineering Investigation should also be closely based on the type of building foundation needs to identify issues related to hydrogeology, to provide the necessary hydrogeological data selection.
1.3 from an engineering perspective, according to the role of groundwater and the impact of the project proposed under different conditions, the evaluation should be focused on geological problems, such as: buried in the ground water level on the basis of the following buildings in the water on the concrete and the corrosion of rebar in concrete. The selection of soft rock, weathered rock, residual soil, expansive soil and other rock and soil bearing layer as a basis for the construction site, should focus on the evaluation of the activities of the rock and soil water potential softening, disintegration, expansion and contraction, etc. effect. In the range of memory compression layer of foundation in loose saturated fine sand, silt on, should have potential erosion forecast, quicksand, the possibility of piping. When the basis of the lower confined aquifer exists, excavation should pressure water washed away after the pit floor to calculate and evaluate the possibility. excavation pit in the ground water level the following should be carried out infiltration and water-rich test, and evaluation of the artificial precipitation caused soil settlement, slope instability and thus the possibility of stability of surrounding buildings.
2 soil hydraulic properties Soil hydraulic properties is the interaction between rock and groundwater who displayed a variety of nature.
Soil hydraulic properties and physical properties of rock are rock: rock and soil hydraulic properties affects not only the strength and deformation of rock and some nature has a direct impact on the stability of the building. In the past the investigation of physical and mechanical properties of the soil test more emphasis on the geotechnical properties of the water management has been neglected, and therefore the evaluation of the geotechnical engineering geology is not comprehensive enough. geotechnical soil water and groundwater management is the nature of the nature of the interaction shown, first of all introduce the following form and occurrence of groundwater on soil hydraulic properties, and then a few of geotechnical important water management research and testing methods of the nature and brief.
2.1 Occurrence in the form of groundwater: groundwater according to their occurrence in the rock can be divided into bound water, capillary water and gravity water three, which combined with water can be divided into strong and weak bound water bound water two.
2.2 The major soil hydraulic properties and test methods: softening refers to the rock mass after immersion in water, characteristics of the mechanical strength decreases, the general said with the softening coefficient, which is to determine the rock resistance to weathering, resistance to flooding capacity indicators. There is easy in the rock layers to soften rocks, in the role of groundwater will often form soft interlayer. all kinds of causes of viscous upper mudstone, shale, argillaceous sandstone Dengjun widespread softening property. permeable, is water under gravity, ground to allow water through their own performance. loose rock particles became smaller, more uniform, its permeability will be weaker. hard rock fissures or karst more development, the stronger its permeability. permeable permeability coefficient of generally available, said upper body rock permeability coefficient of struck by pumping tests.
disintegration, is soaking wet rocks, due to soil particles connections are weakened, damaged, open to soil collapse and disintegration properties. to the water, is fed by gravity from the pore water, soil, fracture properties of the water must flow freely to the degree that water. water level is several important aquifer hydrogeologic parameters also affect the venue sparse time. water level usually determined by laboratory. expansion and shrinkage, refers to rock After the volume of soil water increases, water loss volume was reduced after the characteristics of the sizing of rock is due to thickening of the particle surface adsorbed water absorbent, water loss due to thinning.
3 geotechnical hazards caused by groundwater
Geotechnical hazards caused by groundwater, mainly due to changes in groundwater level and ground lift effect of the hydrodynamic pressure caused by two reasons.
3.1 Groundwater level change caused by the geotechnical hazards. Groundwater level changes can be caused by natural factors or human factors, but for whatever reason, when the groundwater level changes up to a certain extent, will cause harm to the geotechnical engineering, groundwater level changes cause harm can be divided into three ways:
3.1.1 The water level rise caused by the geotechnical hazards. Phreatic reasons for the increase are varied, the main aquifer affected by factors such as geological structure, lithology general occurrence, hydrological and meteorological factors such as rainfall, temperature, etc. and human factors such as irrigation, construction and other effects, it is sometimes combined result of several factors. As the water table rise may result in the geotechnical engineering: soil swamping, salinization, soil and groundwater enhanced corrosion of buildings. slopes, river rock and other rock and soil slippage, landslides and other geological phenomena bad. some of the rock and soil with special structural damage, lower intensity, softening. caused saturated fine sand and silt liquefaction, there quicksand, piping and so on. flooded underground cavern filled with water, basic floating, unstable buildings. reposted elsewhere in the paper for free download http://eng.hi138.com
3.1.2 caused by falling water tables, geotechnical hazards. groundwater bit more than the decrease is due to human factors, such as the concentration of a large number of extraction of groundwater. Deposits in the mining and upstream dam construction dewatering, construction of reservoirs downstream intercept groundwater recharge and so on. Groundwater decline is too large, often induced to crack, ground subsidence, ground collapse and other geological disasters and the depletion of groundwater sources, water quality and other environmental degradation problem, on the rock mass, the stability of buildings and the living environment of human beings posing a great threat.
3.1.3 Groundwater frequent movements of the Geotechnical Engineering harm. Groundwater level change can cause uneven expansion of the expansion and contraction produce rock deformation, when the ground when the lift frequently. Not only on the expansion and contraction deformation of rocks back and forth, and will lead to expansion and contraction of soils and increasing rate, thus causing the building to crack formation, especially of light damage to the building. Groundwater zone change down the infiltration of groundwater, soil will layer of iron and aluminum components leaching, soil cement will result in loss of loose soil, water void ratio increases, the compression modulus, capacity reduction, the basis of geotechnical engineering options to deal with the trouble of bringing greater .
3.2 The role of dynamic pressure caused by ground water geotechnical hazards. Groundwater in the natural state, relatively weak effect of hydrodynamic pressure, usually does not cause any harm, but in the human engineering activities in the dynamic equilibrium due to changes in natural groundwater conditions, the dynamic moving Water pressure, often lead to some serious geotechnical hazards, such as quicksand, piping, etc. FOUNDATION PIT. drift sand, piping, pit formation inrush conditions and control measures in the literature of engineering geology has been more detail not repeated here.
In summary, the hydro-geological work in the building bearing layer selection, basic design, engineering and other aspects of geological disaster prevention plays an important role, along with the development of engineering investigations, the attention will be more widely and effectively do good hydrogeological investigation will raise the level of work plays a great role.
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