Cli­ent: DB Netz AG
Pro­ject aut­hor: IL — Inge­nieur­büro Laab­mayr und Part­ner ZT GmbH
Con­s­truc­tion: ARGE Erneue­rung Kuckucks­lay Tun­nel
Part­ner: PORR GmbH & Co. KGaA | AUGUST REINERS Bau­un­ter­neh­mung GmbH
Tech. Manage­ment: PORR GmbH & Co KGaA
Com­mer­cial manage­ment: AUGUST REINERS Bau­un­ter­neh­mung GmbH
Pro­ject: Rene­wal of Kuckucks­lay­tun­nel rail­road line 2631 Kal­scheue­ren — Ehrang | Trier | Rhi­ne­land-Pala­ti­nate
Period: 2019 to 2022

More space in the tun­nel — that’s what Deut­sche Bahn AG and the miners from Alfred Kunz are hoping for during the tun­nel widening work on the Kuckucks­lay Tun­nel in the Kyll Val­ley on the 2631 Kal­scheue­ren — Ehrang rail­road line near Trier. Alfred Kunz Unter­ta­ge­bau and its part­ner are pre­pa­ring the dou­ble-track, 450-metre-long Kuckucks­lay rail­road tun­nel, which dates back to 1871, for the expan­sion of the rail­road line to the modern track spa­cing of 4.00 m by widening the old tun­nel struc­ture from the impe­rial era. 

In order to main­tain rail ope­ra­ti­ons, the tun­nel widening work is being car­ried out with the help of a tun­nel widening por­tal as well as advance pro­tec­tive enclo­sures with the pos­si­bi­lity of pas­sing through in sin­gle-track rail ope­ra­tion. This tun­nel-in-tun­nel con­s­truc­tion method invol­ves remo­ving the old tun­nel masonry under a rol­ling wheel out­side the pro­tec­tive enclo­sure using a chisel and then remo­ving the ‘fresh’ sand­stone using blas­ting. For this work, the tun­nel exten­sion por­tal was equip­ped with two hydrau­lic demo­li­tion ham­mers and two dril­ling flaps. A steel armor rein­force­ment in the blas­ting area pro­vi­ded opti­mum pro­tec­tion for track sys­tems and rail ope­ra­ti­ons during both mecha­ni­cal chise­ling and blas­ting. The dif­fe­rent excava­tion methods, mecha­ni­cal and explo­sion-based, are neces­sary to ensure the hig­hest pos­si­ble level of safety for rail­road ope­ra­ti­ons and employees as well as an envi­ron­men­tally fri­endly sepa­ra­tion of the con­s­truc­tion mate­ri­als old masonry and sandstone. 

In addi­tion to the cram­ped con­di­ti­ons close to the track in the space bet­ween the field and the pro­tec­tive enclo­sure, the hand­ling of the tar-con­tai­ning old seal­ing and back­pack­ing of the exis­ting tun­nel posed a chall­enge. In order to pre­vent the toxic demo­li­tion waste from being car­ried over from the old masonry and to ensure the hig­hest pos­si­ble level of envi­ron­men­tal pro­tec­tion in the Kyll Val­ley water pro­tec­tion area, an inte­rim manage­ment sys­tem was instal­led to sepa­rate the dirty “black” and clean “white” areas during the tun­nel work. Spe­cial machi­nery from the mining indus­try, such as a loa­der and a loa­ding machine with a loa­ding chute and loa­ding bucket, com­ple­men­ted the mecha­ni­cal excava­tion, blas­ting and secu­ring work, which was car­ried out directly along­side the track ope­ra­tion and was gentle on the rock. The newly instal­led tun­nel inner shell after excava­tion of the sand­stone rock is desi­gned as a water-imper­meable rein­forced con­crete con­s­truc­tion adapted to the rock pressure. 

Due to the wea­the­ring zones in the por­tal areas, which had alre­ady been sub­jec­ted to dis­pla­ce­ment pres­su­res and stres­ses from the con­s­truc­tion of the exis­ting tun­nel in 1871, the two por­tal struc­tures were pro­vi­ded with por­tal covers. While the north por­tal cover was foun­ded on micro­pi­les, the south was foun­ded on incli­ned tan­gen­tial bored piles. Fur­ther­more, an old exis­ting retai­ning wall in the val­ley slope area of the tun­nel apron that was in need of reno­va­tion was repla­ced. For this pur­pose, a tan­gen­tial bored pile wall with a head beam was con­s­truc­ted with a set­back and suc­ces­si­vely ancho­red back during the demo­li­tion work on the old exis­ting wall. 

The great chall­enge of this pro­ject is made up of num­e­rous influen­cing fac­tors. In addi­tion to the extre­mely cram­ped con­di­ti­ons during the excava­tion work, the need to main­tain rail ope­ra­ti­ons led to con­sidera­ble time, space and logi­sti­cal rest­ric­tions. Tog­e­ther with the com­plex and sen­si­tive hand­ling of the demo­li­tion mate­rial ‘old tun­nel struc­ture’ as hazar­dous waste, the reno­va­tion of the Kuckucks­lay­tun­nel requi­red an extre­mely high level of con­cep­tual con­s­truc­tion skills. On com­ple­tion of the work, the engi­neers and miners from Alfred Kunz seam­lessly built on the achie­ve­ments of the tunnel’s con­s­truc­tion in 1871 and crea­ted a con­tem­po­rary, high-qua­lity and dura­ble tun­nel structure. 

TECHNICAL DATA
Struc­tu­ral func­tion: Rail­way tun­nel
Tun­nel length: 450 m
Excava­tion volume: 20,500 m³
Con­s­truc­tion method: Tun­nel within a tun­nel
Tun­nel sup­port: Shot­crete, sup­port arches, anchors, spi­les, spike umbrella