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It was a threat that the lining cavity had a many risk of the tunnel operation, thus detection and prevention was particularly important. The general causes of tunnel lining cavity and corresponding prevention measures will be summarized, and methods which includes detect lining cavity and processing data were given. Last, a real engineering was given for illustrating the practical method of tunnel lining cavity detection process. The proposed method has a great significance to ensure the safety of the tunnel operation.

Homopolymers and copolymers of poly(arylene ether nitrile) (PAEN)-bearing pendant xanthene groups were prepared by the nucleophilic substitution reaction of 2,6-difluorobenzonitrile with 9,9-bis(4-hydroxyphenyl)xanthene (BHPX) and with various molar proportions of BHPX to hydroquinone (100/0 to 40/60) with N-methyl-2-pyrrolidone (NMP) as a solvent in the presence of anhydrous potassium carbonate. These polymers had inherent viscosities between 0.61 and 1.08 dL/g, and their weight-average molecular weights and number-average molecular weights were in the ranges 34,200–40,800 and 17,800–20,200, respectively. All of the PAENs were amorphous and were soluble in dipolar aprotic solvents, including NMP, N,N-dimethylformamide, and N,N-dimethylacetamide and even in tetrahydrofuran and chloroform at room temperature. The resulting polymers showed glass-transition temperatures (Tg's) between 220 and 257°C, and the Tg values of the copolymers were found to increase with increasing BHPX unit content in the polymer. Thermogravimetric studies showed that all of the polymers were stable up to 422°C with 10% weight loss temperatures ranging from 467 to 483°C and char yields of 54–64% at 700°C in nitrogen. All of the new PAENs could be cast into transparent, strong, and flexible films with tensile strengths of 106–123 MPa, elongations at break of 13–17%, and tensile moduli of 3.2–3.7 GPa. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

9,9-Bis(3-methyl-4-hydroxyphenyl)xanthene (BMHPX) was synthesized in 72% yield by a HCl/ZnCl2-catalyzed condensation reaction of xanthenone with excess o-cresol. Based on this new bisphenol monomer, a series of poly(arylene ether nitrile) (PAEN) and PAEN copolymers containing methyl substituent and cardo xanthene moiety were prepared by the nucleophilic substitution reaction of 2,6-difluorobenzonitrile (DFBN) with BMHPX and with varying mole proportions of BMHPX to hydroquinone (HQ) (100/0–40/60) using N-methyl-2-pyrrolidone (NMP) as solvent in the presence of anhydrous potassium carbonate. These polymers had inherent viscosities between 0.54 and 0.72 dl/g, and their weight-average molecular weights and number-average molecular weights were in the range of 32,600–36,400 and 17,300–18,300, respectively. All PAENs were amorphous and were soluble in dipolar aprotic solvents such as NMP and N,N-dimethylacetamide (DMAc), and even in THF and chloroform at room temperature. The resulting polymers showed glass transition temperatures (Tg's) between 213–226°C, and the Tg values of the copolymers were found to increase with increase of the BMHPX units content in the polymer. Thermogravimetric studies showed that all the polymers were stable up to 404°C, with 10% weight loss temperatures ranging from 444 to 455°C, and char yields of 52–58% at 700°C in nitrogen. All new PAENs could be cast into transparent, strong, and flexible films with tensile strengths of 102–120 MPa, elongations at break of 14–18%, and tensile moduli of 3.3–3.7 GPa. Copyright © 2011 John Wiley & Sons, Ltd.

9,9-Bis(4-hydroxyphenyl)xanthene (BHPX) was synthesized in 82% yield from xanthenone in a one-pot, two-step synthetic procedure. A new diacyl chloride monomer, 9,9-bis[4-(chloroformylphenoxy)phenyl]xanthene (BCPX), was synthesized in three steps from the nucleophilic fluorodisplacement of 4-fluorobenzonitrile with the dipotassium bisphenolate of BHPX, followed by alkaline hydrolysis of the intermediate bis(ether nitrile), and then chlorination with thionyl chloride. Several novel aromatic polyamides containing ether and bulky xanthene groups with the inherent viscosities (0.72–0.98 dL/g) were prepared by the low temperature polycondensation of BCPX with various aromatic diamines in N,N-dimethylacetamide (DMAc) solution containing pyridine (Py). All new polyamides were amorphous and readily soluble in various polar solvents such as DMAc, N,N-dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP) and Py. These polymers showed relatively high glass transition temperatures between 236 and 298°C, decomposition temperatures at 10% weight loss ranging from 490 to 535°C and 483 to 515°C in nitrogen and air, respectively, and char yields at 700°C in nitrogen higher than 50%. Transparent, flexible, and tough films of these polymers cast from DMAc solutions exhibited tensile strengths ranging from 82 to 106 MPa, elongations at break from 10% to 25%, and initial moduli from 2.0 to 2.8 GPa.