Introduction
Frozen soil engineering belongs to soil mechanics, which studies the various physical and mechanical properties of frozen soil, the law of freeze-thaw and its changes, the settlement behavior and its mechanism during the thawing process. It provides a theoretical basis and technical means for the design, construction and management of engineering projects constructed on frozen soil ground. At present, geotechnical investigation and engineering design of frozen soil ground has become an important part of civil engineering construction.
Scope and purpose of frozen soil engineering survey
1. Site investigation scope: mainly include ground frozen system and soil property detection, understand its frozen depth, frozen state and activity level, freeze-thaw layer thickness, ice concentration, thawing situation and degree of soil mixture.
2. Purpose of engineering investigation: the purpose of engineering investigation is to obtain the thawing degree and dynamic modulus of frozen soil base and frozen soil layer, understand the infiltration situation of snowmelt and surface runoff during thawing process, determine the boundary of frozen soil base, determine the combined effect of frozen soil and unfrozen soil on engineering foundation and excavation structure, calculate the settlement and deformation of foundation, drainage boundary and stability of slope, and analyze the effect of freeze-thaw on engineering properties of frozen soil and adjacent soil.
Method of frozen soil engineering survey
1. Standard penetration test
It is necessary to carry out the frozen soil boring test to determine the dynamic modulus of frozen soil base and frozen soil layer, understand the infiltration situation of snowmelt and surface runoff during thawing process and determine the boundary of frozen soil base. The peak speed of the penetration is measured by dynamic rapid loading test. The dynamic dynamic modulus of frozen soil base or frozen soil layer at a certain depth is calculated according to its peak speed.
2. temperature logging
Temperature logging is mainly used to determine the frozen depth, frozen state and activity level of frozen soil. The temperature logging test is conducted along the borehole axis by using temperature surveyor. The measured data can be used to calculate the soil thermal conductivity, which is very important in the analysis of soil freezing and thawing process.
3. Melting method static penetration test
Melting method static penetrometer test is a method to investigate the activity level of inorganic freezing and thawing soil. The freezing and thawing of soil cause mechanical and chemical changes, which affect the engineering properties of frozen soil and its freezability. Melting method static penetrometer test is an effective method to measure the activity level of frozen soil and design soil freezing and thawing system.
4. Solidification, melting test
Solidification and melting test is an important means to understand the circular freezing and thawing of frozen soil base and surrounding layers. Ice concentration test and thawing degree test are carried out to understand the freezing and thawing situation of frozen soil, and analyze the physical, mechanical and chemical characteristics of soil in freezing and thawing process, so as to provide a basis for engineering design of frozen soil base and its surrounding layer.
5. Groundwater flow test
It is necessary to determine the infiltration situation of snowmelt and surface runoff during thawing process and the freeze-thaw layer thickness and thawing situation around the frozen soil base. Groundwater flow test is a very important method to investigate the snowmelt and surface runoff infiltration.
Conclusion
Frozen soil engineering investigation is an important basis for engineering design and construction of engineering projects constructed on frozen soil ground. This paper mainly introduces the scope and purpose of frozen soil engineering survey and the methods of frozen soil engineering survey. It is hoped that this article can provide guidance for engineering survey personnel in the field of frozen soil engineering.
