Bearing Characteristics of Confined Concrete Box Steel Arch in Soft Rock Tunnel

doi:10.11988/ckyyb.20241166

Abstract

Abstract:

Confined concrete box steel arch is a composite arch structure comprising box steel and core concrete. It is a novel support form designed to effectively control deformation in soft rock tunnels. Currently, there is limited research on the bearing characteristics of this arch type. In view of this, a compression-bending yield criterion for confined concrete box section is deduced, and the ultimate bearing capacities for strength and structural stability are analyzed respectively. Furthermore, the bearing characteristics of three arch types: confined concrete box steel arch, H-type steel arch, and box steel arch, are compared. Results indicate that the yield criterion value for the confined concrete box steel arch section is the highest among the types considered. Specifically, its axial compression yield limit is 1.4 times that of the box type and 2.2 times that of the H-type. Moreover, the pure bending yield limit is 1.1 times that of the box type and 1.5 times that of the H-type. The strength and ultimate bearing capacity of confined concrete box steel arch surpass those of the box type and H-type steel arches. The ultimate bearing capacity for strength is 1.3-1.4 times that of the box steel arch and 2.2-2.3 times that of the H-type steel arch. The ultimate bearing capacity for structural stability is 1.03-1.04 times that of the box steel arch and 1.10-1.27 times that of the H-type steel arch. Consequently, the confined concrete box steel arch exhibits significant advantages in load-bearing characteristics and can provide reliable and efficient support in soft rock tunnels.

Key words: soft rock tunnel, confined concrete box steel arch, compression-bending yield criterion, strength resistant capability, ultimate bearing capacity of structure stability

HUANG Shu-ling, WANG Xiang-xiang. Bearing Characteristics of Confined Concrete Box Steel Arch in Soft Rock Tunnel[J]. Journal of Changjiang River Scientific Research Institute, 2025, 42(2): 1-8.

Figures/Tables 7

Fig.1Sche matic diagram of confined concrete box steel arch in soft rock tunnel

Fig.2Mech anical analysis model of arch

Fig.3Sect ion drawing of confined concrete box

Table 1 Statistics of compression-bending yield criterion of different sections (Q235 for steel and C40 for concrete)

截面类型	型号	截面压弯屈服判据	N_u/kN	M_u/(kN·m)
约束混凝土箱型截面	150	$\{\begin{array}{l} 1.5290 n^{2} - 0.3921 n + m = 1, n < 0.6574 \\ 0.3632 n^{2} + 1.1405 n + m - 0.5037 = 1, n \geq 0.6574 \end{array}$	2 058	83
	175	$\{\begin{array}{l} 1.5986 n^{2} - 0.4513 n + m = 1, n < 0.6571 \\ 0.3458 n^{2} + 1.1951 n + m - 0.5409 = 1, n \geq 0.6571 \end{array}$	2 638	122
	200	$\{\begin{array}{l} 1.6622 n^{2} - 0.5055 n + m = 1, n < 0.6566 \\ 0.3331 n^{2} + 1.2400 n + m - 0.5731 = 1, n \geq 0.6566 \end{array}$	3 285	172
箱型截面	150	$\{\begin{array}{l} 1.2109 n^{2} + m = 1, n < 0.5392 \\ 0.2180 n^{2} + 1.0707 n + m - 0.2886 = 1, n \geq 0.5392 \end{array}$	1 530	76
	175	$\{\begin{array}{l} 1.2383 n^{2} + m = 1, n < 0.5222 \\ 0.1946 n^{2} + 1.0900 n + m - 0.2846 = 1, n \geq 0.5222 \end{array}$	1 893	112
	200	$\{\begin{array}{l} 1.2648 n^{2} + m = 1, n < 0.5066 \\ 0.1771 n^{2} + 1.1021 n + m - 0.2791 = 1, n \geq 0.5066 \end{array}$	2 286	157
型钢截面	H150型钢	$\{\begin{array}{l} 2.2791 n^{2} + m = 1, n \leq 0.2327 \\ 0.1064 n^{2} + 1.0113 n + m - 0.1177 = 1, n > 0.2327 \end{array}$	919	56
	H175型钢	$\{\begin{array}{l} 2.3151 n^{2} + m = 1, n \leq 0.2296 \\ 0.0992 n^{2} + 1.0176 n + m - 0.1168 = 1, n > 0.2296 \end{array}$	1 174	85
	H200型钢	$\{\begin{array}{l} 2.3470 n^{2} + m = 1, n \leq 0.2268 \\ 0.0939 n^{2} + 1.0220 n + m - 0.1159 = 1, n > 0.2268 \end{array}$	1 459	121

Table 1 Statistics of compression-bending yield criterion of different sections (Q235 for steel and C40 for concrete)

截面类型	型号	截面压弯屈服判据	N_u/kN	M_u/(kN·m)
约束混凝土箱型截面	150	$\{\begin{array}{l} 1.5290 n^{2} - 0.3921 n + m = 1, n < 0.6574 \\ 0.3632 n^{2} + 1.1405 n + m - 0.5037 = 1, n \geq 0.6574 \end{array}$	2 058	83
	175	$\{\begin{array}{l} 1.5986 n^{2} - 0.4513 n + m = 1, n < 0.6571 \\ 0.3458 n^{2} + 1.1951 n + m - 0.5409 = 1, n \geq 0.6571 \end{array}$	2 638	122
	200	$\{\begin{array}{l} 1.6622 n^{2} - 0.5055 n + m = 1, n < 0.6566 \\ 0.3331 n^{2} + 1.2400 n + m - 0.5731 = 1, n \geq 0.6566 \end{array}$	3 285	172
箱型截面	150	$\{\begin{array}{l} 1.2109 n^{2} + m = 1, n < 0.5392 \\ 0.2180 n^{2} + 1.0707 n + m - 0.2886 = 1, n \geq 0.5392 \end{array}$	1 530	76
	175	$\{\begin{array}{l} 1.2383 n^{2} + m = 1, n < 0.5222 \\ 0.1946 n^{2} + 1.0900 n + m - 0.2846 = 1, n \geq 0.5222 \end{array}$	1 893	112
	200	$\{\begin{array}{l} 1.2648 n^{2} + m = 1, n < 0.5066 \\ 0.1771 n^{2} + 1.1021 n + m - 0.2791 = 1, n \geq 0.5066 \end{array}$	2 286	157
型钢截面	H150型钢	$\{\begin{array}{l} 2.2791 n^{2} + m = 1, n \leq 0.2327 \\ 0.1064 n^{2} + 1.0113 n + m - 0.1177 = 1, n > 0.2327 \end{array}$	919	56
	H175型钢	$\{\begin{array}{l} 2.3151 n^{2} + m = 1, n \leq 0.2296 \\ 0.0992 n^{2} + 1.0176 n + m - 0.1168 = 1, n > 0.2296 \end{array}$	1 174	85
	H200型钢	$\{\begin{array}{l} 2.3470 n^{2} + m = 1, n \leq 0.2268 \\ 0.0939 n^{2} + 1.0220 n + m - 0.1159 = 1, n > 0.2268 \end{array}$	1 459	121

Fig.4The m-n curves of different sections

Fig.5Stre ngth resistant capacity of different types of steel arch

Fig.6Ulti mate bearing capacity of structure stability of different types of steel arch

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