地下洞室

地下洞室 Loose rock pressure is caused by rock fracture collapse and block slip and gravity collapse failure pressure, this is a limited range of falling rock mass gravity applied to the tunnel lining on the pressure Foundation bearing capacity: the capacity of a foundation to bear load on its unit area. It is divided into the ultimate bearing capacity and the allowable bearing capacity Karst: water (including surface water and ground water), the chemical dissolution of soluble rock mainly for the transformation and destruction, as well as the resulting topography and hydrogeological phenomena collectively. Karstification: mainly chemical dissolution, including mechanical fragmentation, deposition, collapse and transportation. It is a combination of chemistry and physics. Prevention and control measures of karst leakage: first, to reduce the permeability of rock mass; two, to seal the seepage channel. Measures such as filling, paving, blocking and cutting are often used. Evaluation of 3. ground sliding stability of karst foundation bearing capacity factors less than 2. main forms of karst ground collapse site deformation and failure of the 1. surface: geological structure, strata occurrence, lithology and thickness, cave shape and burial conditions, roof, filling, groundwater, seismic design intensity, building load and the importance of Karst Foundation treatment measures a replacement, repairing, impaction or cross cover, two, beam, arch structure, three span; grouting, blasting packing; four, bottom supporting or adjusting column; five, six, drilling grouting; setting the "cushion"; seven, adjust the area of foundation base; eight, groundwater to. Geotechnical engineering problems of karst origin may occur (1) foundation layer main pressure range, if there is a cave, underground river, the additional load or vibration under the action of karst roof collapse caused by the sudden collapse of foundation. (2) the uneven settlement of foundation is caused by the distribution of soft soil when the foundation is in the main compression layer. (3) covered karst area due to soil cave groundwater activities, gradually lead to surface subsidence, the impact on the site and foundation stability (4) sudden inflow of debris flow and cave rock pressure of underground excavation in Karst rock, the deformation and failure of surrounding rock is called surrounding rock pressure on the supporting lining the pressure on the. Surrounding rock resistance: lining deformation and transmission of pressure to the surrounding rock, then the surrounding rock will produce a reaction force, known as the resistance of the surrounding rock. Underground chambers: artificial excavation or natural existence in rock and soil, as a variety of structures, collectively known as underground chambers, also known as underground buildings or underground works. Underground caverns can be divided according to their purpose of traffic tunnel, hydraulic tunnel, mine tunnel, underground workshop and warehouse, underground railway and underground military engineering type (1) according to whether there is the inner wall of the internal pressure can be divided into non pressure tunnel and pressure cavern two; (2) according to the section shape can be divided into round, rectangular, arched and horseshoe type; according to the relationship between the tunnel axis and horizontal plane can be divided into horizontal and inclined shaft tunnels and caverns three; (3) according to the surrounding rock types can be divided into two types of soil cave and cave; (4) in addition to artificial and natural cavern excavation points and so on. Underground mining area: the underground space left by man for digging underground resources. It can be divided into three categories: old mined out area, existing mined out area and future mined out area according to the present mining situation. Surface movement basins: when underground mining affects the surface of the earth, The surface of the goaf will form a depression basin. The developed surface movement basin can be divided into three areas: middle area (homogeneous subsidence area), inner edge area (moving zone) and outer fringe area (slight deformation area). The deformation forms: sink (vertical displacement), horizontal displacement (tension and compression), tilt, bending (curvature); goaf surface deformation: the horizontal deformation of orebody was produced, from the top layer to form the three slate belt, caving zone and fractured zone and bending with water guide. From the vertical perspective, is divided into three zones: the caving zone (caving zone) the fracture zone (with the band bending bending rupture) (crack bending zone) of goaf surface deformation factors. The 1 Factors: the buried depth of ore beds) is larger and longer extended to the required surface deformation the time, the smaller the value of surface deformation, relatively flat and uniform deformation, the surface movement range large basin. The greater the thickness of the seam, the greater the mined out area, which increases the deformation value of the ground surface. The larger the dip angle is, the greater the horizontal displacement is, the more likely the surface cracks will occur, and the positions of the basins and the mined out areas are also asymmetrical. 2) lithology factors: when the overlying rock strength is high and the monolayer thickness is large, the deformation and failure process of the overlying strata is long, and it is difficult to affect the surface. Some hard rock formations of large thickness do not even produce surface deformation for long periods of time, whereas low strength and thin layer rocks are the opposite. Brittle rocks tend to crack, while plastic strata tend to exhibit uniform settlement. In addition, the thicker the surface Quaternary deposits are, the greater the surface deformation value is, but the deformation is even and uniform. 3) geological structure factors: when rock stratum joint fracture develops, it will promote deformation plus block, enlarge deformation range and enlarge surface fracture area. The fault will destroy the normal law of surface deformation, change the range and position of the mobile basin, and the surface deformation on the fault zone will be more intense. 4) groundwater factors: groundwater activity will speed up the deformation rate, expand the scope of deformation, and increase its surface deformation value. 5) mining conditions: seam mining and roof treatment methods, the size and shape of the mined out area, and the advancing speed of the working face all affect the surface deformation value, deformation speed and deformation mode. Methods: the survey of mined out area is mainly based on data collection, mining survey, engineering drilling, geophysical exploration, and deformation observation, hydrology test analysis and evaluation of goaf stability: mainly through the calculation of foundation bearing capacity, residual surface deformation and residual hole stability and surface damage to the range. There are many theories and methods for predicting mining subsidence. The main contents are as follows: (1) based on the empirical formula of measured data, the exponential function method and typical curve method are widely used in our country. (2) probability integral method widely used in our country. Goaf architectural design principles: construction planning, according to the analysis of the prediction results and the construction suitability zoning results of surface deformation, select the favorable site planning; then, the locations and types of buildings and the construction measures of A axis azimuth etc., building shape simple, symmetrical, flat shape with rectangular or square is appropriate and each part of the same height, B, setting settlement joint, will be complex, and the length is too long or the load stiffness difference between the larger buildings, It is divided into several independent units with simple shape, short length and uniform stiffness and load. Structural measures A adopt concrete or reinforced concrete cross bar foundation to increase the integrity and rigidity of foundation. B, set the ring beam and the vertical and horizontal symmetry through walls, to increase the building's integrity and stiffness, improve the shear and flexural tensile strength, brick masonry. C, in order to improve the shear strength of the wall and increase the overall stiffness of the building when the surface curvature deformation is large, the reinforced concrete structural column can be set up in the wall with large shear force or the corner of the wall of the unit. The qualitative evaluation of the stability of the surrounding rock (1) broken loose rock or soft plastic rock distribution area, including rock weathering, tectonic fracture zone and weathering speed, low mechanical strength, easy water softening, swelling or disintegration of soil drilling rocks distribution zone; (2) cataclastic rock and semi the hard thin bedded structure rock mass distribution area; (3) the hard lump shape and thick bedded rock, cutting, in the top or side wall of unstable structure into several groups of weak structural plane parts. Quantitative evaluation of surrounding rock stability: local block stability analysis method of vector graphic method (the solid scale projection) the analytic method of rock overall stability analysis method in numerical simulation. The foundation refers to the buildings below support foundation soil or rock mass; the bearing capacity of the foundation: refers to the ability of foundation soil per unit area under load; settlement refers to the ground surface layer under the additional stress caused by compaction sinking of the geotechnical engineering deep foundation pit excavation problems: (1 excavation and analysis of soil pressure; (2 (at the bottom of the pit excavation stability analysis of unloading, the bottom of the foundation pit seepage stability, foundation pit quicksand, foundation pit slope stability; (3) groundwater control (pit dewatering, foundation pit water. )