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TB 10035-2018: Code for Design on Special Railway Earth Structure
TB 10035-2018
INDUSTRY STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
UDC
P TB 10035-2018
J 158-2018
Code for Design on Special Railway Earth Structure
ISSUED ON: OCTOBER 12, 2018
IMPLEMENTED ON: JANUARY 1, 2019
Issued by: National Railway Administration of the PRC
Table of Contents
1 General ... 11 
2 Terms and symbols ... 13 
2.1 Terms ... 13 
2.2 Symbols ... 17 
3 Subgrade of soft soil section ... 19 
3.1 General provisions ... 19 
3.2 Stability analysis and settlement calculation ... 22 
3.3 Embankment ... 31 
3.4 Cutting ... 33 
3.5 Foundation treatment ... 35 
4 Earth structure of expansive rock and soil ... 39 
4.1 General provisions ... 39 
4.2 Embankment ... 40 
4.3 Cutting ... 41 
4.4 Slope protection and reinforcement ... 43 
4.5 Foundation treatment ... 45 
4.6 Subgrade waterproof and drainage ... 46 
5 Loess subgrade ... 48 
5.1 General provisions ... 48 
5.2 Embankment ... 49 
5.3 Cutting ... 50 
5.4 Slope protection and reinforcement ... 52 
5.5 Foundation treatment ... 52 
5.6 Subgrade waterproof and drainage ... 56 
5.7 Sinkhole treatment ... 57 
6 Saline soil and salt rock subgrade ... 58 
6.1 General provisions ... 58 
6.2 Embankment ... 58 
6.3 Side slope protection ... 61 
6.4 Foundation treatment ... 62 
6.5 Subgrade waterproof and drainage ... 63 
7 Earth structure of permafrost area ... 65 
7.1 General provisions ... 65 
7.2 Embankment ... 66 
7.3 Cutting ... 69 
7.4 Slope protection and retaining ... 70 
7.5 Transition section ... 71 
7.6 Subgrade waterproof and drainage ... 73 
7.7 Borrow pits and spoil banks ... 75 
8 Earth structure of seasonal frozen soil area ... 76 
8.1 General provisions ... 76 
8.2 Embankment ... 76 
8.3 Cutting ... 79 
8.4 Subgrade retaining and protection ... 80 
8.5 Subgrade waterproof and drainage ... 82 
9 Earth structure of granite weathered residual soil ... 83 
9.1 General provisions ... 83 
9.2 Embankment ... 84 
9.3 Cutting ... 85 
9.4 Slope protection and reinforcement ... 86 
9.5 Subgrade waterproof and drainage ... 88 
10 Subgrade of filling site ... 90 
10.1 General provisions ... 90 
10.2 Embankment ... 91 
10.3 Cutting ... 91 
10.4 Foundation treatment ... 94 
10.5 Subgrade waterproof and drainage ... 96 
11 Subgrade of landslide section ... 97 
11.1 General provisions ... 97 
11.2 Landslide stability analysis and sliding force calculation ... 97 
11.3 Prevention and control engineering ... 99 
11.4 Engineering landslide prevention... 102 
11.5 Landslide monitoring ... 103 
12 Subgrade of dangerous rock, rockfall, collapse and talus section ... 105 
12.1 General provisions ... 105 
12.2 Subgrade of dangerous rock, rockfall, and collapse section ... 105 
12.3 Subgrade of talus section ... 106 
13 Subgrade of karst and artificial pothole section ... 108 
13.1 General provisions ... 108 
13.2 Subgrade of karst section ... 109 
13.3 Subgrade of artificial pothole section ... 112 
14 Subgrade in area of sand blown by the wind ... 115 
14.1 General provisions ... 115 
14.2 Embankment ... 116 
14.3 Cutting ... 117 
14.4 Subgrade slope protection ... 117 
14.5 Plane protection of sand blown by the wind ... 118 
14.6 Windproof measures in windy areas ... 122 
15 Subgrade of snow-damaged area ... 124 
15.1 General provisions ... 124 
15.2 Subgrade section form ... 125 
15.3 Protective measures ... 125 
16 Submerged subgrade ... 128 
16.1 General provisions ... 128 
16.2 Subgrade of pond and waterlogged sections ... 131 
16.3 River beach and riverside subgrade ... 131 
16.4 Coastal subgrade ... 132 
16.5 Subgrade of reservoir section ... 135 
Appendix A Classification and relevant characteristics of special rock and soil
... 138 
Appendix B Calculation of foundation settlement and thickness of insulation
layer in permafrost ... 153 
Appendix C Calculation of load of sand blown by the wind ... 165 
Appendix D Calculation method of buried depth of sand barrier column
foundation ... 166 
Descriptions for word use of this Code ... 169 
2 Terms and symbols
2.1 Terms
2.1.1 Earth structure of special area
The general term for earth structure of special rock and soil area and earth
structure of special condition.
2.1.2 Earth structure of special rock and soil area
The earth structure located in special rock and soil sections such as soft soil,
expansive rock and soil, loess, saline soil.
2.1.3 Earth structure of special condition
The earth structure located in bad geological sections, as well as the earth
structure strongly affected by natural factors such as water and climate.
2.1.4 Soft soil
The cohesive soil deposited in still water or slow flowing water environment and
characterized by large water content (w≥wL), large void ratio (e≥1.0), high
compressibility (a0.1~0.2≥0.5 MPa-1), and low strength (Ps< 0.8 MPa).
2.1.5 Loose-soft soil
The strata such as cohesive soil, silt, and sandy soil that cannot reach the soft
soil index in the earth structure engineering, which are characterized by larger
water content or void ratio, higher compressibility (a0.1~0.2≥0.25 MPa-1), and
lower strength or bearing capacity (σ0≤150 kPa).
2.1.6 Expansive soil
The cohesive soil in which clay minerals are mainly composed of hydrophilic
minerals and which has the characteristics of water swelling, softening,
disintegration, and rapid shrinkage and cracking from water loss, and can
produce reciprocating deformation.
2.1.7 Loess
The soil, formed under arid and semi-arid climatic conditions since the
Quaternary, whose particles are mainly composed of powder particles and
contain calcium carbonate and a small amount of soluble salts, and which has
the engineering geological characteristics such as macro-void and vertical
joints, poor water resistance, easy disintegration and subsurface erosion, and
3 Subgrade of soft soil section
3.1 General provisions
3.1.1 Soft soil can be classified according to its physical and mechanical
properties in accordance with Appendix A.0.1 of this Code. Subgrade shall
consider its following engineering characteristics and effects:
1 Soft soil has the characteristics of low natural strength and high
compressibility, resulting in poor subgrade stability and large foundation
settlement deformation.
2 Soft soil has the characteristics of low permeability and slow consolidation.
The consolidation of the foundation lasts a long time. The consolidation
time and its settlement amount vary greatly with the consolidation
conditions, which affects the post-construction settlement of subgrade and
construction period control of deep thick soft soil foundation.
3 When the high-sensitivity soft soil has thixotropy, construction vibration and
disturbance will cause the strength of the soft soil to be seriously reduced,
affecting the stability, deformation, or safe use of existing projects around
the construction period.
4 High-plasticity or over-consolidated soft soil has rheological properties.
Under undrained shear conditions, it will lead to more long-term strength
reduction and continuous increase of deformation of soft soil, affecting
long-term stability, deformation control, and surrounding environment
safety of the subgrade.
3.1.2 Loose-soft soil can be classified according to its physical and mechanical
properties in accordance with Appendix A.0.1 of this Code. Subgrade stability,
post-construction settlement control shall consider its engineering
characteristics such as low strength, high compressibility or easy liquefaction
and influences.
3.1.3 The subgrade of the soft soil section should be in the form of embankment.
Its height should not be less than the thickness of the foundation bed. The
choice of subgrade location shall meet the following requirements:
1 It is advisable to choose a section with narrow area and thin thickness of
soft soil.
2 In low hilly areas, closed or semi-closed depressions should be avoided.
3 In the valley between mountains, it is advisable to avoid being located in
φi - The internal friction angle of the bottom of the ith soil strip (°);
Ei-1 - Sliding force of the i-1-th soil strip transferring the ith soil strip (kN);
φi-1 - Transfer coefficient of remaining sliding force.
5 When the embankment base is reinforced with geosynthetics, the tensile
force it bears shall be calculated as the slide-resisting force.
3.2.3 When using composite foundation treatment, the overall sliding stability
analysis of the embankment and the foundation shall be based on geological
conditions, composite foundation type, and possible failure modes; adopt
appropriate methods; and, shall meet the following requirements:
1 The composite foundation of discrete material piles and of reinforced soil
piles in general sections can, in accordance with subclause 3.2.2 of this
Code, be checked and computed by the arc method or the unbalanced
thrust transfer coefficient method. According to the stratum and range of
the slip circle cutting, the composite foundation shall respectively adopt the
shear strength index of the composite or natural foundation soil. When
using discrete material piles, the drainage consolidation effect on the
foundation can be considered; the shear resistance of the soil between the
piles, increased by consolidation under the load of the embankment, can
be considered.
2 Rigid pile composite foundation, and reinforced soil pile composite
foundation in sections with complex conditions such as high embankment,
soft soil characteristics, or environmental sensitivity shall be analyzed
according to the possible failure modes of the composite foundation, using
appropriate methods or combining numerical methods. When the arc
method is used for analysis, the influencing factors such as soft soil
characteristics and pile-soil modulus ratio shall be fully considered; the
form and effect of pile-soil load sharing shall be reasonably determined;
and, the sliding surface force shall be calculated. If necessary, the
horizontal bearing capacity of the pile should be calculated, to check the
lateral stability of the pile.
3.2.4 When using rigid pile foundation treatment, the stability of the
embankment shall be analyzed according to the rigid pile foundation of the pile-
supported embankment; and, shall meet the following requirements:
1 The vertical bearing capacity of the rigid pile foundation of the pile-
supported embankment shall meet the vertical load requirements of the
embankment above the pile top. The vertical allowable bearing capacity of
a single pile shall be determined according to the following formula:
3.3.4 The boundary between embankment and other structures, the section
with large strata change, and the junction of different foundation treatment
measures shall adopt gradual transition foundation treatment measures, to
reduce uneven settlement.
3.3.5 Embankment design using drainage consolidation method for foundation
treatment shall comply with the following provisions:
1 Through the stability check analysis during the construction period, the
construction instructional design shall be conducted on the filling
parameters, such as the critical height of rapid filling, embankment filling
loading form, stepped height and loading time (including precompression).
The critical height of filling can also be determined by empirical formula
calculation.
2 When constructing a new embankment and reserving the second line, it is
advisable to design a double-line embankment at a time.
3 In accordance with the construction organization arrangement and the
construction period requirements, the construction shall be arranged in
advance. After the embankment filling construction is completed, it shall
be placed for a period of time. If necessary, the load can be increased for
precompression.
3.3.6 The subgrade of ballasted track railway with design speed of 200 km/h
and below shall be reserved for post-construction settlement widening of the
subgrade. The widening value on each side shall be calculated and determined
according to the post-construction settlement and the slope ratio of the track
bed slope.
3.3.7 Embankment shoulders should be made of dry masonry stones or precast
concrete blocks. When using mortar masonry stones or precast concrete blocks
or cast-in-place concrete, it shall strengthen measures to prevent longitudinal
uneven settlement and ensure smooth transverse drainage of foundation bed.
When the post-construction settlement is large, the road camber or its
transverse drainage slope should be enlarged. If necessary, on the top or
bottom surface of the foundation bed surface layer, an impermeable layer may
be set.
3.3.8 When the subgrade base on the subgrade on the soft soil foundation in
the earthquake area adopts sand and gravel cushion, the cushion material shall
be gravel (pebble) or coarse gravel (pebble). Fine sand must not be used. It is
not suitable to use medium and coarse sand for the embankment base cushion
in earthquake areas of 9 degrees and above.
3.3.9 Based on conditions such as embankment filler properties, slope height,
3.4.3 According to the nature of the weak soil, thickness, bottom lateral slope,
hydrogeological conditions, and types of reinforcement measures, etc., using
the circular sliding method or the unbalanced thrust method, the cutting slope
shall be subjected to stability analysis according to the relevant provisions of
section 3.2 of this Code. Combined with factors such as slope height,
environmental conditions, construction methods, it shall comprehensively
determine the slope form, slope ratio, and the load size and distribution
characteristics of rock-soil pressure or sliding force acting on the retaining
structure.
3.4.4 Slope reinforcement protection and retaining measures shall be
determined according to the engineering geological and hydrogeologi...