1 replacement method
1.1 filling replacement
The embankment height is small, the general use of processing filling replacement method for soft soil foundation. If the thickness of soft soil is more than 3m, usually only excavated a portion of the soft soil, replacement of strength and stability are better materials. First, the replacement of all or part of the peat soft soil excavation, and the use of water permeability, good stability of the material (adding cement or lime when necessary) were stratified filling.
1.2 rubble law
Low-lying areas agelong seeper, when drainage difficulty, silt generally assumes the flow state, the thickness of 3~4m, the surface without obvious shell, stone easy acquisition of the lot, and the stones sink into the mud at the bottom of the condition can use jackstone method. Compaction construction materials by not easily weathered, good stability of stone, stone size is determined by the consistency to peat. For the easy flow of peat or mud, stones in 80% above should be more than 30cm diameter, reduce the amount of mud to a minimum.
1.3 the geotextile reinforced foundation
By using geotextile as reinforcement of foundation reinforcement material, the use of its reinforcement, reinforcement, stress diffusion and drainage to improve the bearing capacity of foundation and adjust the deformation of foundation, often used in conjunction with sand cushion. Pad soil vibration in soft ground fabric can make the load uniform distribution; in the high filled embankment, can be properly stratified isolator.
2 drainage consolidation method
2.1 bags of manhole
The bagging sand well is the quality to meet the requirements of the sand first into good water permeability, woven bag, and then using the sink or into the equipment will be installed to sink into the soft land base of sandbags. Bagged manholes are both large diameter manhole role, and can guarantee the continuity of the manhole, avoid necking phenomenon. In addition, due to the smaller pore diameter of sand bagged manholes, little material consumption, low engineering cost, construction speed is accelerated apparently, is the best method for construction of soft foundation. When the mud or soft soil thickness greater than 5m, and the height of subgrade soil weight far exceed the bearing capacity of natural foundation and foundation soil horizontal displacement is larger, bagged manholes have obvious advantages, is the soft soil foundation treatment method is the most suitable.
2.2 manholes
First of all, drilling holes in the soft soil foundation, with coarse, sand, coarse, using load acceleration of soft soil water discharged from the sand, the processing method for manhole. Consolidation accounting for a large proportion of soil and high plasticity clay is not used, are suitable for the rest of the soft soil with manhole method.
2.3 sand cushion
The top surface of the soft soil in the laying of drainage sand, in order to increase the drainage surface, the consolidation of soft soil foundation and accelerate the drainage under embankment loads, enhance its strength, meet the requirement of stability. Effect of drainage sand substrate for distribution of stress and settlement size without significantly, but can accelerate the development of settlement, shorten the consolidation process. When filling the road base in the sand cushion when the embankment filling speed should be reasonable arrangements, to increase the bearing capacity of foundation loading rate and (drainage consolidation) rate adaptation, to ensure that the foundation is not destroyed during the embankment filling. Displacement can usually use of embedded in the embankment midline ground settlement plate and arranged in the embankment at the foot of the side pile construction observation, keep abreast of the situation and development trend of ground deformation in embankment process, so as to judge whether the stability of foundation.
2.4 plastic drainage plate
Plastic drainage plate is evolved based on cardboard drain on, its features are: single hole cross section, smooth drainage, light weight, high strength, good durability. Usually this method is adopted in the peat saturated silt sections or subgrade soft, high underground water level condition. On 3 light embankment settlement and stability of embankment construction method for soft soil in embankment filling weight, use of lightweight filler can increase the stability of embankment and reduce the settlement. Light filling construction method is the use of large styrene foam block (EPS) light embankment construction. EPS block because of light weight, convenient transportation, easy construction. Fill or abutment, back packing light material is most appropriate, can significantly reduce the ground deformation and subsidence, prevent and connection structure of fault, but also can reduce the transverse impact on the surrounding ground. In order to reduce the deformation of embankment, increase the overall stability of embankment stability, prevent oil infiltration damage of EPS, as a part of the road, can be directly in EPS cast-in-place reinforced concrete slab as a protective layer, and then complete the construction of pavement layer thereon. The compressive strength of EPS is low, the use of traditional construction of rolling equipment must be careful when working, to prevent damage to the light material.
4 composite foundation treatment method
4.1 deep mixing method
Deep mixing method is through a special machine, the curing agent and the foundation soil in situ forming method of forced mixing cement soil pile in foundation reinforcement depth.
Composite foundation of deep mixing method to form has the following characteristics:
(1) the pile body is longer, the smaller the spacing, the better result of treatment.
(2) consolidation of soft foundation treated slow stirring method, soft soil consolidation degree is small.
(3) most of the stress concentration on the pile body, part of stress transfer to the underlying soil in composite foundation by pile body, increases the settlement, composite foundation of soil layer below therefore, powder spraying method must penetrate the soft soil layer, otherwise the soft foundation settlement increase, consolidation rate slowed down, not to the reinforcement of soft foundation the effect of.
(4) and lateral composite subgrade deformation small, inside two months after filling to the displacement tends to be stable. The construction method not only can improve the stability of structures and reduce settlement, but also can be used for special