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1.
Frost heave is an upward swelling of soil during cryogenic conditions in cold regions. It is caused by the accumulation of ice crystals in subgrade soil, which grow upwards when freezing temperatures penetrate into the subgrade. This study establishes the allowable soil subgrade frost heave based on the roughness standard of asphalt pavement in China, and aims to balance the pavement design and frost heave resistance of subgrades in cold regions. We formulated a mechanical model of pavement supported by the boundary conditions of differential frost heave, based on the elastic layered system theory. The differential soil subgrade frost heave was modeled as a sinusoidal function, and the allowable frost heave and the roughness index were modeled as the displacement boundaries for the top and bottom of the pavement structure. Then the allowable frost heave was back-calculated according to the roughness standard. Numerical results show that the allowable frost heave depends on the pavement structure, material properties, the highway grade, and other factors. In order to ensure that the actual soil subgrade frost heave is lower than the allowable frost heave, pavement structures and materials need to be selected and designed carefully. The numerical method proposed here can be applied to establish the frost heave resistance of subgrade when the pavement structure and materials are determined. 相似文献
2.
In the cold regions of northern China, incidents of municipal underground gas pipeline rupture and leakage occur quite frequently,
most often in winter. To prevent harm to citizen safety and property, analysis of the causes of such cracking and leakage is therefore
valuable. Two incident analyses are discussed here and the reasons why most of these types of cases occur during winter are clarified.
The effects of vehicle loadings above buried pipelines are calculated and compared with the effects and calculations of frost heaving
forces. We demonstrate that when the soil layer above a pipeline freezes rapidly, the soil generates repeated frost heaving, which exerts
heaving forces on the pipeline that can result in fatigue crack propagation and ultimate pipeline failure. Therefore, the incident induced
by frost heaving is one of the primary reasons of gas pipeline failure. Based on these analyses, we present some recommendations
pertaining to the proper design, construction, and management of gas pipelines. 相似文献
3.
Kazakhstan regions is seasonal climatic with transient freezing of soil groundduring the winter. Roadbed integrity is important to resist the sustained load transmitted by traffic on the road surface. Freezing of soil ground could significantlyinfluence roadbed integrity in the seasonal freezing climate of Kazakhstan. The proper determination magnitude of frost heave and heaving pressure by the influence of freezing temperatures during the winter season are necessary for design and construction of highways. Thus, experimental tests were conducted on specimens obtained from Astana (Kazakhstan) to determine the freezing pressure and magnitude of frost heaving. 相似文献
4.
Fine round gravel soil is widely employed in the subgrade of high speed railways in cold regions to prevent frost heaving
and thawing. The lower the fines content in fine round gravel soil, the smaller the quantities of frost heaving and thawing,
but compaction difficulty increases. This study is to obtain the optimum fines content and limited frost heaving and
thawing. The fine round gravel soil filling (FRGSF) used in the Harbin-Qiqihaer Passenger Dedicated Line is taken as the
study object. Influence of fines content on optimum water content, maximum dry density and frost heaving properties of
FRGSF were studied by means of compaction and frost heaving tests. Results show that the maximum dry density of the
FRGSF increases first and then decreases with an increase of fines content, namely there is an optimum fines content for
easy compaction. The method of surface-vibratory instrument is fit for coarse-grained soils, and wet state of
coarse-grained soil is in favor of compaction. Considering the relationship of fines content with maximum dry density and
the frost heaving ratio of FRGSF, the fines content should be limited to within the range of 9%-10%, so that the frost
heaving ratio is less than 1%, and the FRGSF is easily compacted. Water supply is proved to be an important factor influencing
the amount of frost heaving of FRGSF. We also conclude that in the field, it is imperative to control waterproofing
and drainage measures. 相似文献
5.
Earth structures, such as roadways, embankments and slopes, and earth retaining walls, have been commonly used in cold regions for transportation and other applications. In addition to typical design c... 相似文献
6.
This paper aims to determine the optimal fines content of coarse-grained soil required to simultaneously achieve weaker frost susceptibility and better bearing capacity. We studied the frost susceptibility and strength properties of coarse-grained soil by means of frost heaving tests and static triaxial tests, and the results are as follows:(1) the freezing temperature of coarse-grained soil decreased gradually and then leveled off with incremental increases in the percent content of fines; (2) the fines content proved to be an important factor influencing the frost heave susceptibility and strength properties of coarse-grained soil. With incremental increases in the percent content of fines, the frost heave ratio increased gradually and the cohesion function of fines effectively enhanced the shear strength of coarse-grained soil before freeze-thaw, but the frost susceptibility of fines weakened the shear strength of coarse-grained soil after freeze-thaw; (3) with increasing numbers of freeze-thaw cycles,the shear strength of coarse-grained soil decreased and then stabilized after the ninth freeze-thaw cycle, and therefore the mechanical indexes of the ninth freeze-thaw cycle are recommended for the engineering design values; and (4) considering frost susceptibility and strength properties as a whole, the optimal fines content of 5% is recommended for railway subgrade coarse-grained soil fillings in frozen regions. 相似文献
7.
This paper set up a series of comprehensive targets based on the concept of 'anti-freeze filler', which include reasonable water retention rate, frost heave characteristics, and compaction characteristics of filling material. Then, a type of permeable graded gravel is proposed, suitable for high-speed railway subgrade. A series of in-door water retention, permeability, and frost heave tests were performed under different graded conditions. Water retention, permeability, and frost heave characteristic of different graded filling materials can be determined, in order to define the gradation range of permeable graded gravel. Relying on the frost-heave monitoring record of high speed railway in Northeast China, a series of experimental studies were performed, which included on-site filler production, compaction test, and the anti-frost effect test, in order to improve the production and compaction techniques of permeable graded gravel. From the research of this paper, the use of permeable graded gravel subgrade as the anti-frost structure for the high-speed railway subgrade in cold areas is feasible. 相似文献
8.
This paper presents methods for monitoring frost heave, device requirements, testing principals, and data analysis requirements, such as manual leveling observation, automatic monitoring (frost heave, frost depth, and moisture), track dynamic detection, and track status detection. We focused on the requirements of subgrade frost heave monitoring for high speed railways, and the relationship of different monitoring methods during different phases of the railway. The comprehensive monitoring system of high speed railway subgrade frost heave provided the technical support for dynamic design during construction and safe operation of the rail system. 相似文献
9.
Based on the similarity theory, taking the horseshoe, city-gate and round linings as examples, the value and distribution regularities of normal frost heaving pressures （hereinafter as frost heaving pressures） in tunnels excavated in fractured rock mass in cold regions under different constraints and freezing depths were studied by a test model. It was found that the larger the frozen depth, the larger the frost heaving pressure, and the stronger the top constraint, the larger the frost heaving pressure. For the horseshoe lining and city-gate lining, the top constraint has a greater effect on the frost heaving pressures on the arch and the inverted arch. For the round lining, the influences of the top constraint on the frost heaving pressure in all linings are almost the same. The frost heaving pressure is maximum on the city-gate lining and minimal on the round lining. The largest frost heaving pressure all occur near the foot of the inverted arch for the three kinds of lining. Thus, the test data basically coincide with the observed in situ data. 相似文献
10.
A new experiment method is introduced to study the relations between frost heaving strain and stress of soil or fracture rock under different moisture contents, temperatures and stress states. Based on experiments, a new triaxial frost heaving stress-strain relation is presented aiming at tunnel in cold regions. The experimental equipments are strain-controlled and low temperature buildup, and different restrained conditions are controlled by changing the stiffness of a test-force-ring. Then the frost heaving strain and stress of soil or fracture rock can be obtained under different restrained conditions, and the frost heaving stress-strain relation can be got by regression analysis of some feature points. Experiments of saturated sandy soil conducted by this method show that the triaxial frost heaving stress-strain relation could be expressed by logarithmic curves, and the frost heaving stress changes linearly with the logarithm of the frost heaving strain. The stronger the constraint, the smaller the frost heaving strain and the larger the frost heaving stresses. The frost heaving stresses would tend to a limit value with increasing the constraint intensity. The larger the confining pressure, the larger the frost heaving strain and stress. 相似文献
11.
According to the technical characteristics of short fixed wheelbase of a high-speed carriage, a subgrade-track integrated space mechanical response analysis model is proposed for trains under the action of biaxial load after the comparison of the stress distribution characteristics of the ballast track subgrade bed structures for high-speed railway under the action of uniaxial load and biaxial load. The loading threshold value (high-cycle long-term dynamic strength) under the circumstance where the cumulative deformation of subgrade structure gradually develops and finally reaches the convergent state, and its relationship with the foundation coefficient K30 were deduced, based on the characteristics of cumulative deformation evolution obtained from the unit structure filling model test under the action of cyclic loading. In view of structure stability and frost resistance requirements of the railway subgrade in cold regions, technical conditions to maintain good service performance of subgrade structure of high-speed railway ballasted track are discussed and analyzed. Study results show that the additive effect manifests itself obviously for railway train bogies under the action of biaxial load than uniaxial load, which has a significant dynamic effect on the subgrade bed bottom and a slight effect on the surface layer. Thus, the adoption of a biaxial load model in the design of a high-speed railway subgrade accurately reflects the vehicle load. Pursuant to the structure design principle, the design method of the subgrade structure of high-speed railway ballasted track is proposed to meet the technical requirements such as structural strength, bearing stiffness and high-cyclic and long-term stability. Technical indicators are obtained for the variation of thickness of the surface layer of reinforced subgrade bed in the double-layer subgrade mode along with the change of K30 at the subgrade bed bottom. The double-layer structure mode of "closure on the upper layer and drainage on the lower layer" was proposed in order to meet the waterproofing and drainage requirements of the upper layer of the subgrade bed in cold regions. A dense-framework graded gravel filler with weak water permeability at a coefficient of 10-4 cm/s is used on the upper layer and the void-framework graded gravel filler at the water permeability coefficient of 10-2 cm/s is adopted on the lower layer. 相似文献
12.
13.
Satoshi Akagawa 《寒旱区科学》2021,13(2):77-86
Since the 1970's, frozen ground has been developing near the Tokyo Bay area around liquefied natural gas(LNG) inground storage tanks. For disaster prevention purposes, the tanks are constructed below the ground surface. Since the temperature of the liquid stored in the tanks is -162℃ the soil surrounding the tanks freezes. Since this frozen ground has existed for almost half a century, we have permafrost near Tokyo. The development of artificial frozen ground may cause frost heaving, resulting in frost heave forces that may cause structural damage of adjacent LNG in-ground storage tanks.Therefore, the demand for frozen ground engineering increased and consequently we now have advanced technology in this area. Fortunately, we use this engineering technology and artificial ground freezing for civil engineering, especially in big and crowded cities like Tokyo. This paper provides a summary of the testing apparatus, test methods, and assessment methods for frost heaving. 相似文献
14.
The operation of a railway track in cold regions results in the premature deformation of subgrade soils caused by significant temperature fluctuations and ecological imbalance. Identification and calculation of the thawing degree of permafrost soils, frost heaving of clays, and groundwater flooding require careful engineering and geological surveying. The paper describes the unique, long-standing experience of the university scientists connected with maintaining the Russian East-Siberian and Trans-Baikal Railways'' facilities. Specific features of and requirements for the surveying, depending on the geological and climatic conditions, are identified. 相似文献
15.
The developed vertical coupling model of Vehicle-Track-Subgrade which considered subgrade layer vibration is present-ed. The equations of motion for the ballast, top and bottom subgrade layers are pres... 相似文献
16.
Frost heave is one of the major complications in highway construction in cold regions. Laboratory experiments are im-portant in the study frost heave behavior of soils, and one-dimensional frost heave ... 相似文献
17.
A series of saline soil-related problems, including salt expansion and collapse, frost heave and thaw settlement, threaten the safety of the road traffic and the built infrastructure in cold regions. This article presents a comprehensive review of the physical and mechanical properties, salt migration mechanisms of saline soil in cold environment, and the countermeasures in practice. It is organized as follows:(1) The basic physical characteristics;(2) The strength criteria and constitutive models;(3) Water and salt migration characteristics and mechanisms; and(4) Countermeasures of frost heave and salt expansion. The review provides a holistic perspective for recent progress in the strength characteristics, mechanisms of frost heave and salt expansion, engineering countermeasures of saline soil in cold regions. Future research is proposed on issues such as the effects of salt erosion on concrete and salt corrosion of metal under the joint action of evaporation and freeze-thaw cycles. 相似文献
18.
DaiChao Sheng 《寒旱区科学》2021,13(2):87-94
Frost susceptibility is a concept widely used in cold region geotechnical design, to quantify the capacity of a soil in generating frost heave and frost damage. The laboratory test used to verify frost susceptibility of a soil is based on the measurement of frost heave generated in the soil under specific conditions. In reality this concept is, however, more related to the soil's potential to thaw weakening than to frost heave. Recent experimental studies show that frost non-susceptible soils like clean sand and clean gavel can also generate much ice segregation and frost heave if the conditions are favourable, hence challenging the usefulness and suitability of soil classification based on frost susceptibility. It is further shown that the concept is not suitable for design scenarios where frost heave itself is a serious hazard, such as in high-speed rail embankments. 相似文献
19.
The uneven frost heave of frost-susceptible subgrade soil causes track irregularity, which highly enhances train vibration and affects the comfort and safety of railway transportation. This paper presents a coupled thermo-hydro-mechanical (THM) analysis for the freezing behavior of railway located above a box culvert. The vertical acceleration of the vehicle, an indicator of riding comfort, is predicted through a vehicle dynamic model. The results reveal that the existence of a box culvert changes the subgrade thermal pattern, leading to a deeper frost penetration depth. The frost heave amount above the box culvert is larger than the adjacent section, resulting in uneven track structure upheave and track irregularity. This frost-induced track irregularity highly affects train vibration. 相似文献
20.
Alexander Isakov 《寒旱区科学》2013,5(4):0353-0362
The main reasons for a breach of trouble-free operation of the subgrade are the different kinds of deformation, such as train load impact on
subgrade surface, loss of stability to subgrade slope, weight of embankment on the base, and partial or complete failure of the railway track
due to frost heaving. This paper gives a summary of deformation analysis methods being developed in Russia to estimate the operating conditions
of the railway subgrade. 相似文献